Semiconductor light emitting device

ABSTRACT

The present invention relates to a vertical/horizontal light-emitting diode for a semiconductor. An exemplary embodiment of the present invention provides a semiconductor light-emitting diode comprising: a conductive substrate; a light-emitting structure including a first conductive semiconductor layer, an active layer and a second conductive semiconductor layer sequentially formed over the conductive substrate; a second conductive electrode including a conductive via that passes through the first conductive semiconductor and active layers to be connected with the second conductive semiconductor layer therein, and an electrical connector that extends from the conductive via and is exposed outside the light-emitting structure; a passivation layer for covering a dielectric and at least the side surface of the active layer of the light-emitting structure, the dielectric serving to electrically isolate the second conductive electrode from the conductive substrate, the first conductive semiconductor layer and the active layer; and a surface relief structure formed on the pathway of light emitted from the active layer. According to the present invention, a semiconductor light-emitting diode exhibiting enhanced external light extraction efficiency, especially the diode&#39;s side light extraction efficiency, can be obtained.

TECHNICAL FIELD

The present invention relates to a semiconductor light emitting device,and more particularly, to a semiconductor light emitting device withimproved external light extraction efficiency.

BACKGROUND ART

A semiconductor light emitting device is a semiconductor device whichemits light of various colors by the recombination of electrons andholes in a p-n junction between a p-type semiconductor and an n-typesemiconductor when a current is applied thereto. When compared with afilament-based light emitting device, a semiconductor light emittingdevice has a longer lifespan, lower power consumption, superior initialdriving characteristic, higher vibration resistance, and so on. Hence,the demand for semiconductor light emitting device is continuouslyincreasing. Specifically, a great deal of attention has recently beenpaid to a group III nitride semiconductor which can emit light in ashort-wavelength region, such as a series of blue colors.

A nitride single-crystal, which constitutes a light emitting deviceusing a group III nitride semiconductor, is formed over a substrate forspecific single-crystal growth, e.g., a sapphire substrate or a SiCsubstrate. However, there are considerable limitations on thearrangement of electrodes when an insulation substrate, such as asapphire substrate, is used. Specifically, in the case of a conventionalnitride semiconductor light emitting device, electrodes are generallyarranged in a horizontal direction, which causes a narrow current flow.Such a narrow current flow increases an operating voltage (Vf) of thenitride semiconductor light emitting device, which degrades currentefficiency. In addition, the nitride semiconductor light emitting deviceis vulnerable to electrostatic discharge. To solve these problems, thereis a need for a nitride semiconductor light emitting device having anoptimized chip structure and electrode structure.

DISCLOSURE Technical Problem

An aspect of the present invention provides a vertical/horizontal typesemiconductor light emitting device which is capable of improvinginternal/external light efficiency, specifically, external lightextraction efficiency through the optimization of an electrode structureand a device structure.

Technical Solution

According to an aspect of the present invention, there is provided asemiconductor light emitting device, including: a conductive substrate;a light emitting structure including a first-conductivity typesemiconductor layer, an active layer, and a second-conductivity typesemiconductor layer which are sequentially formed on the conductivesubstrate; a second-conductivity type electrode including a conductivevia passing through the first-conductivity type semiconductor layer andthe active layer and connected to the inside of the second-conductivitytype semiconductor layer, and an electrical connection part extendingfrom the conductive via and exposed to the outside of the light emittingstructure; an insulator electrically separating the second-conductivitytype electrode from the conductive substrate, the first-conductivitytype semiconductor layer, and the active layer; a passivation layerformed to cover at least a side surface of the active layer in the lightemitting structure; and an uneven structure formed on a path of lightemitted from the active layer.

According to another aspect of the present invention, there is provideda semiconductor light emitting device, including: a conductivesubstrate; a light emitting structure including a first-conductivitytype semiconductor layer, an active layer, and a second-conductivitytype semiconductor layer which are sequentially formed on the conductivesubstrate; a first contact layer electrically connected to thefirst-conductivity type semiconductor layer between the conductivesubstrate and the first-conductivity type semiconductor layer andexposed to the outside of the light emitting device; a conductive viaextending from the conductive substrate, passing through the firstcontact layer, the first-conductivity type semiconductor layer, and theactive layer, and electrically connected to the inside of thesecond-conductivity type semiconductor layer; an insulator electricallyseparating the conductive substrate from the first contact layer, thefirst-conductivity type semiconductor layer, and the active layer; apassivation layer formed to cover at least a side surface of the activelayer in the light emitting structure; and an uneven structure formed ona path of light emitted from the active layer.

The semiconductor light emitting device may further include a secondcontact layer formed between the first-conductivity type semiconductorlayer and the conductive substrate and electrically separated from thesecond-conductivity type electrode by the insulator.

The light emitting structure may be formed only on a portion of the topsurface of the conductive substrate, and an etch stop layer formed on atleast a region in which the light emitting structure is not formed overthe top surface of the conductive substrate, the etch stop layer havingan etching characteristic different from a semiconductor materialconstituting the light emitting structure.

The uneven structure may be formed on the top surface of thesecond-conductivity type semiconductor layer.

The first-conductivity type semiconductor layer and thesecond-conductivity type semiconductor layer may be a p-typesemiconductor layer and an n-type semiconductor layer, respectively.

DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view of a semiconductor light emitting device accordingto an embodiment of the present invention;

FIG. 2 is a cross-sectional view of the semiconductor light emittingdevice of FIG. 1;

FIG. 3 is a graph showing an n-type ohmic contact resistance and ap-type ohmic contact resistance in a semiconductor light emitting devicehaving an area of 1,000×1,000 μm²;

FIG. 4 is a graph showing a total resistance of a first contactresistance and a second contact resistance according to a contact areabetween a first semiconductor layer and a first electrode layer;

FIG. 5 is a graph showing the luminous efficiency according to thecontact area between the first semiconductor layer and the firstelectrode layer;

FIG. 6 illustrates a modified embodiment of the semiconductor lightemitting device of FIG. 2;

FIG. 7 is a cross-sectional view of a semiconductor light emittingdevice according to another embodiment of the present invention;

FIGS. 8 and 9 show simulation results when an n-type specific contactresistance is varied;

FIGS. 10 through 14 illustrate a semiconductor light emitting deviceaccording to another embodiment of the present invention;

FIGS. 15 through 18 illustrate a semiconductor light emitting deviceaccording to another embodiment of the present invention;

FIGS. 19 through 23 illustrate a semiconductor light emitting deviceaccording to another embodiment of the present invention;

FIGS. 24 through 34 illustrate a semiconductor light emitting deviceaccording to another embodiment of the present invention;

FIGS. 35 through 55 illustrate a semiconductor light emitting deviceaccording to another embodiment of the present invention;

FIGS. 56 through 75 illustrate a semiconductor light emitting deviceaccording to another embodiment of the present invention;

FIGS. 76 through 89 illustrate a semiconductor light emitting deviceaccording to another embodiment of the present invention;

FIGS. 90 through 100 illustrate a semiconductor light emitting deviceaccording to another embodiment of the present invention;

FIGS. 101 through 119 illustrate a semiconductor light emitting deviceaccording to another embodiment of the present invention;

FIGS. 120 through 122 illustrate white light emitting device packagesaccording to various embodiments of the present invention;

FIG. 123 is an emission spectrum of a white light emitting deviceaccording to an embodiment of the present invention;

FIGS. 124A through 124D are wavelength spectrums illustrating anemission characteristic of a green phosphor used herein;

FIGS. 125A and 125B are wavelength spectrums illustrating an emissioncharacteristic of a red phosphor used herein;

FIGS. 126A and 126B are wavelength spectrums illustrating an emissioncharacteristic of a yellow phosphor used herein;

FIGS. 127 through 129 illustrate an emission spectrum, an XRD spectrum,and an EDX component analysis result of a phosphor expressed as (Sr,M)₂SiO_(4-x)N_(y) according to a first embodiment of the presentinvention;

FIGS. 130 and 131 illustrate an emission spectrum and an EDX componentanalysis result of a phosphor expressed as (Sr, M)₂SiO_(4-x)N_(y)according to first and second embodiments of the present invention;

FIG. 132 illustrates an emission spectrum of a phosphor expressed as(Sr, M)₂SiO_(4-x)N_(y) according to fourth through sixth embodiments ofthe present invention;

FIG. 133 illustrates an emission spectrum of a phosphor expressed as(Sr, M)₂SiO_(4-x)N_(y) according to seventh through tenth embodiments ofthe present invention;

FIG. 134 illustrates an emission spectrum of a phosphor expressed as(Sr, M)₂SiO_(4-x)N_(y) according to an eleventh embodiment of thepresent invention;

FIGS. 135 through 137 are graphs illustrating an X-ray diffractionanalysis result, an emission spectrum, and an excitation spectrum of aβ-SiAlON phosphor manufactured according to a twelfth embodiment of thepresent invention;

FIGS. 138A and 138B illustrate a light emitting device package accordingto another embodiment of the present invention;

FIGS. 139 through 141 illustrate a light emitting device packageaccording to another embodiment of the present invention;

FIGS. 142 and 143 illustrate a structure of a lamp-type light emittingdevice package and a chip-type light emitting device package accordingto embodiments of the present invention, respectively;

FIGS. 144 and 145 illustrate a partial structure of a light emittingdevice package according to another embodiment of the present invention;

FIGS. 146 and 147 are schematic views illustrating an energy transitionbetween a green phosphor (second phosphor) and a red phosphor (firstphosphor) used in the light emitting device package;

FIGS. 148 and 149 are a cross-sectional view of a light emitting devicepackage and a schematic view a light extraction mechanism according toanother embodiment of the present invention;

FIGS. 150 through 152 are cross-sectional views of a light emittingdevice package according to another embodiment of the present invention;

FIG. 153 is a schematic cross-sectional view of a light emitting devicepackage according to another embodiment of the present invention;

FIG. 154 is a schematic perspective view of a wavelength conversion partand a control part in the light emitting device package of FIG. 153;

FIGS. 155 and 156 are cross-sectional views illustrating a method ofchanging a color temperature through the operation of the wavelengthconversion part and the control part in FIG. 153;

FIGS. 157 and 158 are schematic views of light emitting device packagesaccording to various embodiments of the present invention;

FIG. 159 is a schematic view illustrating a process of forming anexternal lead frame in the light emitting device package of FIG. 157;

FIGS. 160 and 161 are schematic side sectional views illustrating whitelight source modules according to various embodiments of the presentinvention;

FIG. 162 is a schematic plan view illustrating the arrangement structureof a light emitting modules in a surface light source according to anembodiment of the present invention;

FIG. 163 illustrates a rotation arrangement method of the light emittingmodules of FIG. 162;

FIGS. 164 through 167 are schematic plan views illustrating thearrangement structures of light emitting modules in a surface lightsource according to various embodiments of the present invention;

FIG. 168 is a cross-sectional view of a backlight unit used in surfacelight sources according to various embodiments of the present invention;

FIG. 169 is a perspective view of a surface light source according toanother embodiment of the present invention;

FIGS. 170 and 171 are schematic views of a surface light source and aplate-type light guide plate according to another embodiment of thepresent invention;

FIGS. 172 through 177 illustrate a backlight unit having a plate-typelight guide plate according to another embodiment of the presentinvention;

FIGS. 178 through 182 are schematic views of a backlight unit accordingto another embodiment of the present invention;

FIGS. 183 through 187 are schematic views of LED driver circuitsaccording to various embodiments of the present invention;

FIG. 188 is a configuration diagram of an automatic LED dimmingapparatus according to an embodiment of the present invention;

FIG. 189 is a flowchart illustrating the operation of the automatic LEDdimming apparatus of FIG. 188;

FIG. 190 is an external luminance-detection voltage relationship graphof the automatic LED dimming apparatus of FIG. 188;

FIG. 191 is an external luminance-detection voltage relationship graphaccording to the sensitivity setting of the automatic LED dimmingapparatus of FIG. 188;

FIG. 192 is an exploded perspective view of a vehicle headlightaccording to an embodiment of the present invention;

FIG. 193 is a cross-sectional view illustrating an assembly of thevehicle headlight of FIG. 192; and

FIGS. 194 through 197 are schematic views of light emitting devicepackages adopted in the vehicle headlight of FIG. 192 according tovarious embodiments of the present invention.

MODE FOR INVENTION

Exemplary embodiments of the present invention will now be described indetail with reference to the accompanying drawings. The invention may,however, be embodied in many different forms and should not be construedas being limited to the embodiments set forth herein. Rather, theseembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the invention to thoseskilled in the art. In the drawings, the thicknesses of layers andregions are exaggerated for clarity. Like reference numerals in thedrawings denote like elements, and thus their description will beomitted.

It will be understood that when an element is referred to as being“connected to” another element, it can be directly connected to theother element or intervening elements may also be present. In contrast,when an element is referred to as being “directly connected to” anotherelement, there are no intervening elements present. In addition, unlessexplicitly described to the contrary, the word “comprise” and variationssuch as “comprises” or “comprising,” as well as the word “include” andvariations such as “includes” and “including,” will be understood toimply the inclusion of stated elements but not the exclusion of anyother elements.

Semiconductor light emitting devices, according to exemplary embodimentsof the present invention, will be described in detail, and lightemitting device packages and backlight apparatuses using thesemiconductor light emitting devices will be then described in detail.

<Semiconductor Light Emitting Device>

FIGS. 1 and 2 are a plan view and a cross-sectional view, respectively,of a semiconductor light emitting device according to an embodiment ofthe present invention. Specifically, FIG. 2 is a cross-sectional viewtaken along line I-I′ of FIG. 1.

Referring to FIGS. 1 and 2, a semiconductor light emitting device 100according to an embodiment of the present invention includes aconductive substrate 110, a first electrode layer 120, an insulationlayer 130, a second electrode layer 140, a second semiconductor layer150, an active layer 160, and a first semiconductor layer 170, all ofwhich are stacked sequentially.

The conductive substrate 110 may be formed of a material through whichelectricity may flow. The conductive substrate 110 may be formed of amaterial including any one of Au, Ni, Al, Cu, W, Si, Se, and GaAs, forexample, SiAl which is a combination of Si and Al.

The first electrode layer 120 is provided over the conductive substrate110. Since the first electrode layer 120 is electrically connected tothe conductive substrate 110 and the active layer 160, the firstelectrode layer 120 may be formed of a material which minimizes contactresistance between the conductive substrate 110 and the active layer160.

As illustrated in FIG. 2, the first electrode layer 120 provided overthe conductive substrate 110 also extends through a contact hole 180,which passes through the insulation layer 130, the second electrodelayer 140, the second semiconductor layer 150, the active layer 160, anda predetermined region of the first semiconductor layer 170, so that thefirst electrode layer 120 comes into contact with the firstsemiconductor layer 170. Consequently, the conductive substrate 110 andthe first semiconductor layer 170 are provided so that they areelectrically connected together.

Specifically, the first electrode layer 120 electrically connects theconductive substrate 110 to the first semiconductor layer 170 throughthe contact hole 180. The conductive substrate 110 and the firstsemiconductor layer 170 are electrically connected together through thesize of the contact hole 180, more exactly, the contact region 190 wherethe first electrode layer 120 and the first semiconductor layer 170contact each other through the contact hole 180.

Meanwhile, the insulation layer 130 is provided over the first electrodelayer 120 to electrically insulate the first electrode layer 120 fromthe other layers, except for the conductive substrate 110 and the firstsemiconductor layer 170. Specifically, the insulation layer 130 isprovided between the first electrode layer 120 and the second electrodelayer 140, and between the first electrode layer 120 and side surfacesof the second electrode layer 140, the second semiconductor layer 150,and the active layer 160, which are exposed by the contact hole 180.Furthermore, the insulation layer 130 may also be provided on sidesurfaces of the predetermined region of the first semiconductor layer180 through which the contact hole 180 passes.

The second electrode layer 140 is provided over the insulation layer130. As described above, the second electrode layer 140 is not providedin the predetermined regions through which the contact hole 180 passes.

In this case, as illustrated in FIG. 2, the second electrode layer 140includes at least one exposed region 145, i.e., a region where a portionof the interface with the second semiconductor layer 150 is exposed. Anelectrode pad portion 147 may be provided in the exposed region 145 inorder to connect an external power supply to the second electrode layer140. Meanwhile, the second semiconductor layer 150, the active layer160, and the first semiconductor layer 170, which will be describedlater, are not provided in the exposed region 145. Moreover, asillustrated in FIG. 1, the exposed region 145 may be formed at edges ofthe semiconductor light emitting device 100 in order to maximize thelight emitting area of the semiconductor light emitting device 100.

Meanwhile, the second electrode layer 140 may be formed of a materialincluding Ag, Al, Pt, Ni, Pd, Au, Ir, or a transparent conductive oxide.This is because the second electrode layer 140 electrically contacts thesecond semiconductor layer 150, and thus, the second electrode layer 140must have a characteristic which minimizes the contact resistance of thesecond semiconductor layer 150 and a function which increases theluminous efficiency by reflecting light generated at the active layer160 to the outside.

The second semiconductor layer 150 is provided over the second electrodelayer 140, and the active layer 160 is provided over the secondsemiconductor layer 150. Also, the first semiconductor layer 170 isprovided over the active layer 160.

In this case, the first semiconductor layer 170 may be an n-type nitridesemiconductor, and the second semiconductor layer 150 may be a p-typenitride semiconductor.

Meanwhile, a material of the active layer 160 may be differentlyselected according to materials of the first semiconductor layer 170 andthe second semiconductor layer 150. Specifically, since the active layer160 is a layer which converts energy generated from electron-holerecombination into light and emits the converted light, the active layer160 may be formed of a material having a smaller energy band gap thanthe first semiconductor layer 170 and the second semiconductor layer150.

FIG. 6 illustrates a modified embodiment of the semiconductor lightemitting device of FIG. 2. The semiconductor light emitting device 100′of FIG. 6 is substantially similar to the semiconductor light emittingdevice 100 of FIG. 2, except that a passivation layer 191 is provided onsides of the light emitting structure, which includes the secondsemiconductor layer 159, the active layer 160, and the firstsemiconductor layer 170, and the top surface of the first semiconductorlayer 170 is uneven. The passivation layer 191 protects the lightemitting structure, specifically the active layer 160, from the outside.The passivation layer 191 may be formed of silicon oxide, siliconnitride, or other insulating materials, e.g., SiO₂, SiO_(x)N_(y), orSi_(x)N_(y) and may be approximately 0.1-2 μm in thickness. The activelayer 160 exposed to the outside may act as a current leakage pathduring the operation of the semiconductor light emitting device 100′.However, such a problem can be prevented by forming the passivationlayer 191 on the sides of the light emitting structure. In this case, asillustrated in FIG. 6, when the uneven passivation layer 191 may improvethe light extraction efficiency. Likewise, the top surface of the firstsemiconductor layer 170 may be uneven. The first semiconductor layer 170having the uneven top surface increases the probability that light willbe emitted to the outside in a direction of the active layer 160.Although not illustrated, in a case in which the light emittingstructure is etched in order to expose the second electrode layer 140 inthe fabrication process, an etch stop layer may be further be formedover the second electrode layer 140 in order to prevent the material ofthe second electrode layer 140 from being attached to the side surfaceof the active layer 160. The above-described modified embodiment of thepresent invention illustrated in FIG. 6 may be applied to an embodimentof the present invention illustrated in FIG. 7.

Meanwhile, the semiconductor light emitting device suggested in thisembodiment of the present invention may be modified in theabove-described structure so that the first electrode layer connected tothe contact hole is exposed to the outside. FIG. 7 is a cross-sectionalview of a semiconductor light emitting device according to anotherembodiment of the present invention. A semiconductor light emittingdevice 200 according to another embodiment of the present inventionincludes a second semiconductor layer 250, an active layer 260, and afirst semiconductor layer 260 over a conductive substrate 210. In thiscase, a second electrode layer 240 may be provided between the secondsemiconductor layer 250 and the conductive substrate 210. Unlike thepreceding embodiment, the second electrode layer 240 is not necessarilyrequired. In this embodiment, a contact hole 280, having a contactregion 290 which contacts the first semiconductor layer 270, iselectrically connected to a first electrode layer 220, and the firstelectrode layer 220 is exposed to the outside and has an electricconnection portion 245. An electrode pad portion 247 may be formed inthe electric connection portion 245. An insulation layer 230 may beprovided to electrically separate the first electrode layer 220 from theactive layer 260, the second semiconductor layer 250, the secondelectrode layer 240, and the conductive substrate 210. As opposed to theforegoing embodiment in which the contact hole is electrically connectedto the conductive substrate, the contact hole 280 is electricallyseparated from the conductive substrate 210, and the first electrodelayer 220 connected to the contact hole 280 is exposed to the outside.Hence, the conductive substrate 210 is electrically connected to thesecond semiconductor layer 240, so that the polarity is different fromthe foregoing embodiment.

Hereinafter, the optimum size and shape of the contact hole will befound through the simulation of the variation in the electricalcharacteristics according to the contact area between the firstelectrode layer and the first semiconductor layer in the semiconductorlight emitting devices suggested in the embodiments of the presentinvention. The following simulation results can be applied to both thestructure of FIG. 1 and the structure of FIG. 6. In this simulation, thefirst semiconductor layer and the second semiconductor layer wereimplemented with an n-type semiconductor layer and a p-typesemiconductor layer, respectively.

FIG. 3 is a graph showing n-type ohmic contact resistance and p-typeohmic contact resistance in a semiconductor light emitting device havinga size of 1,000×1,000 μm².

In the simulation of FIG. 3, an n-type specific contact resistance,i.e., a specific contact resistance between the first electrode layerand the contact hole is 10⁻⁴ Ω/cm², and a p-type specific contactresistance, i.e., a specific contact resistance between the secondsemiconductor layer and the second electrode layer is 10⁻² Ω/cm².

Referring to FIG. 3, when assuming that the semiconductor light emittingdevice 100 according to this embodiment of the present invention is arectangular chip having a size of 1,000-μm×1,000-μm, i.e., 1,000,000μm², the semiconductor light emitting device 100 has a first contactresistance of the first semiconductor layer 170 and the first electrodelayer 120, and a second contact resistance of the first electrode layer120, the second electrode layer 140, the first semiconductor layer 170,and the second semiconductor layer 150. The first contact resistance R1and the second contact resistance R2 vary greatly according to contactarea.

In particular, it can be seen from FIG. 3 that, as the contact areaincreases, the first contact resistance R1 changes more than the secondcontact resistance R2. In FIG. 3, the X-axis represents the magnitude ofthe contact area between the first semiconductor layer 170 and the firstelectrode layer 120, and the Y-axis represents the magnitude of thecontact resistance. Therefore, the number on the X-axis means thecontact area between the first semiconductor layer 170 and the firstelectrode layer 120, and the contact area between the secondsemiconductor layer 150 and the second electrode layer 140, whichcorresponds to the second contact resistance R2, is calculated bysubtracting the value of the X-axis from the total area (1,000,000 μm²)of the semiconductor light emitting device 100.

In this case, as described above with reference to FIGS. 1 and 2, thecontact area between the first semiconductor layer 170 and the firstelectrode layer 120 is equal to a total area of the contact region 190where the first electrode layer 120 and the first semiconductor layer170 are in contact with each other through the contact hole 180. Thatis, since the contact hole 180 is provided in plurality, the contactarea between the first semiconductor layer 170 and the first electrodelayer 120 is equal to the sum of the areas of the respective contactregions 190.

FIG. 4 is a graph showing a total resistance of the first contactresistance and the second contact resistance according to the contactarea between the first semiconductor layer and the first electrodelayer.

Referring to FIG. 4, since the first contact resistance R1 and thesecond contact resistance R2 are serially connected in the semiconductorlight emitting device 100 according to the embodiment of the presentinvention, the total resistance R3 obtained by combining the firstcontact resistance R1 and the second contact resistance R2 is theresistance which is most greatly influenced according to the contactarea among all of the resistances of the semiconductor light emittingdevice 100.

It can be seen from FIG. 4 that the total resistance R3 (see the valueof the Y-axis) rapidly decreases at the start as the contact area (seethe value of the X-axis) between the first semiconductor layer 170 andthe first electrode layer 120 increases, and then, the total resistanceR3 increases as the contact area between the first semiconductor layer170 and the first electrode layer 120 increases.

Meanwhile, when the semiconductor light emitting device 100 is 1,000,000μm² in size, it is preferable that the n-type contact resistance and thep-type contact resistance are approximately 1.6Ω or less. Thus, it ispreferable that the contact area between the first semiconductor layer170 and the first electrode layer 120 is in the range of approximately30,000-250,000 μm².

The typical operating voltage of the semiconductor light emitting deviceis in the range of approximately 3.0-3.2 V, and the typical operatingvoltage of the semiconductor light emitting device is approximately 0.35A. If the total resistance of the semiconductor light emitting device isapproximately 2Ω, the voltage is equal to 0.70 V (=0.35(A)×2(Ω)), whichis out of the normal specification range (i.e., 2.8 V to 3.8 V). Assuch, if out of the voltage range, the existing circuit configurationneeds to be modified, and the increase of the input power may cause thegeneration of heat and the degradation of light output. Therefore, it ispreferable that the total resistance of the semiconductor light emittingdevice is 2Ω or less. In the semiconductor light emitting devicesuggested in this embodiment of the present invention, the sum of then-type contact resistance and the p-type contact resistance isapproximately 80% of the total resistance. Thus, the reference contactresistance may be 1.6Ω(=2(Ω)×0.8).

Specifically, the semiconductor light emitting device 100 describedabove with reference to FIGS. 1 and 2 is most preferable in view ofcontact resistance when the total contact area of the contact regions190, where the first electrode layer 120 and the first semiconductorlayer 170 are in contact with each other through the contact hole 180,is in the range of approximately 30,000 μm-250,000 μm².

FIG. 5 is a graph showing the luminous efficiency according to thecontact area between the first semiconductor layer and the firstelectrode layer.

According to the description made with reference to FIG. 4, it seemsthat when the contact area between the first semiconductor layer 170 andthe first electrode layer 120 is in the range of approximately30,000-250,000 μm², the total resistance of the semiconductor lightemitting device 100 is low and thus the luminous efficiency is high.However, there is no consideration on the fact that the practical lightemitting area of the semiconductor light emitting device 100 is reducedwith the increase in the contact area between the first semiconductorlayer 170 and the first electrode layer 120.

That is, as illustrated in FIG. 5, the luminous efficiency of thesemiconductor light emitting device 100 increases because the totalresistance is reduced until the contact area between the firstsemiconductor layer 170 and the first electrode layer 120 is equal to70,000 μm², but the luminous efficiency of the semiconductor lightemitting device 100 decreases if the contact area between the firstsemiconductor layer 170 and the first electrode layer 120 increases tomore than 70,000 μm². The increase in the contact area between the firstsemiconductor layer 170 and the first electrode layer 120 means thecontact area between the second semiconductor layer 150 and the secondelectrode layer 140 decreases, causing the reduction in the lightemitting amount of the semiconductor light emitting device 100.

Therefore, it is important to appropriately determine the contact areabetween the first semiconductor layer 170 and the first electrode layer120. As illustrated in FIG. 5, it is preferable that the contact areabetween the first semiconductor layer 170 and the first electrode layer120 be 130,000 μm² or less, at which level the luminous efficiencybecomes 90% or more.

Consequently, in the semiconductor light emitting device 100 accordingto this embodiment of the present invention, it is most preferable thatthe contact area between the first semiconductor layer 170 and the firstelectrode layer 120 through the contact hole 180 is in the range ofapproximately 30,000-130,000 μm². This is the case in which the chipsize of the semiconductor light emitting device 100 is 1,000,000 μm².Hence, the most preferable contact area between the first semiconductorlayer 170 and the first electrode layer 120 is in the range ofapproximately 3-13% of the area of the semiconductor light emittingdevice 100.

Meanwhile, when the number of the contact holes 180 is too small, thecontact area between the first semiconductor layer 170 and the firstelectrode layer 120 with respect to one contact region 190 between thefirst semiconductor layer 170 and the first electrode layer 120increases. However, the area of the first semiconductor layer 170 towhich a current is supplied also increases, thus increasing the amountof current, which must be supplied from the contact region 190.Consequently, a current is crowded in the contact region 190 between thefirst semiconductor layer 170 and the first electrode layer 120.

On the other hand, when the number of contact holes 180 is too large,the size of the contact hole 180 becomes too small, causing difficultiesin the fabrication process.

Therefore, the number of contact holes 180 is appropriately determinedaccording to the size of the semiconductor light emitting device 100,i.e., the chip size. When the size of the semiconductor light emittingdevice 100 is 1,000,000 μm², it is preferable that the number of thecontact holes 180 is 5 to 150.

Meanwhile, the plurality of contact holes 180 may be disposed uniformlyin the semiconductor light emitting device 100. The first semiconductorlayer 170 and the first electrode layer 120 are contacted through thecontact holes 180. Thus, in order to uniformly disperse the current, itis preferable that the contact holes 180 are disposed uniformly, thatis, the contact regions 190 between the first semiconductor layer 170and the first electrode layer 120 are disposed uniformly.

When the size of the semiconductor light emitting device 100 is1,000,000 μm² and the number of the contact holes 180 is 5 to 150, thespacing between the adjacent contact holes 180 may be in the range fromapproximately 100-400 μm in order to ensure the uniform arrangement ofthe semiconductor light emitting device. The spacing between theadjacent contact holes 180 is a value measured by connecting the centerpoints of the adjacent contact holes 180.

Meanwhile, the semiconductor light emitting device 100 obtains theuniform current dispersion by uniformly disposing the plurality ofcontact holes 180 as described above. Thus, a semiconductor lightemitting device having a size of 1,000,000 μm², according to the priorart, operates at approximately 35 mA, but the semiconductor lightemitting device according to this embodiment of the present inventionoperates very stably even though a high current of approximately 2 Å isapplied, and the current crowding phenomenon is also reduced, therebyimproving the reliability of the semiconductor light emitting device.

FIGS. 8 and 9 show simulation results when the n-type specific contactresistance is varied. In this simulation, the n-type specific contactresistance is 10⁻⁶ Ω/cm², and the p-type specific contact resistance is10⁻² Ω/cm². The n-type specific contact resistance is affected by thedoping concentration of the n-type semiconductor layer, the n-typeelectrode material, the thermal treatment method thereof, and so on.Thus, the n-type specific contact resistance may be reduced to 10⁻⁶Ω/cm² by increasing the doping concentration of the n-type semiconductorlayer, or employing a material having a low metal energy barrier, e.g.,Al, Ti, Cr, etc., as the n-type electrode material. In other words, thecommonly used n-type specific contact resistance may be in the range ofapproximately 10⁻⁴-10⁻⁶ Ω/cm².

Referring to FIG. 8, when compared with the simulation result of FIG. 4,the sum of the n-type specific contact resistance and the p-typespecific contact resistance, i.e., the total contact resistance R4, canbe maintained at a very low level even with a small contact area. Inaddition, when compared with the luminous efficiency of FIG. 5, theluminous efficiency of FIG. 8, according to contact area, can bemaintained at a high level, even with a small contact area. In thiscase, more than 100% of the luminous efficiency represents a relativevalue with reference to the result of FIG. 5. Referring to thesimulation results of FIGS. 8 and 9, the total contact resistancebecomes 1.6Ω or less and the luminous efficiency becomes 90% or morewhen the contact area between the first electrode layer and the firstsemiconductor layer is in the range of approximately 6,150-156,800 μm²in the semiconductor light emitting device having a size of 1,000,000μm².

When determining the number of contact holes on the basis of the aboveresults, the contents described in the above simulation results may beapplied. Specifically, in the case of a circular contact hole having aradius of approximately 1-50 μm, approximately 1-48,000 contact holesare required in order to meet the above-described area condition.Furthermore, when assuming that the contact holes are uniformlydisposed, the spacing between the two adjacent contact holes is in therange of approximately 5-500 μm.

Next, semiconductor light emitting devices, according to variousembodiments of the present invention, will be described in detail.

A semiconductor light emitting device, according to another embodimentof the present invention, will be described with reference to FIGS. 10through 14.

A semiconductor light emitting device 300, according to anotherembodiment of the present invention, includes a conductive substrate340, a first-conductivity type semiconductor layer 330, an active layer320, and a second-conductivity type semiconductor layer 310, which arestacked in sequence. In particular, the semiconductor light emittingdevice 300 according to this embodiment of the present inventionincludes: a first electrode layer 360 between the conductive substrate340 and the first-conductivity type semiconductor layer 330; and asecond electrode part 350 including an electrode pad portion 350-b, anelectrode extension portion 350-a, and an electrode connection portion350-c.

The electrode pad portion 350-b extends from the first electrode layer360 to the surface of the second-conductivity type semiconductor layer310, and is electrically separated from the first electrode layer 360,the first-conductivity type semiconductor layer 330, and the activelayer 320. The electrode extension portion 350-a extends from the firstelectrode layer 360 to the inside of the second-conductivity typesemiconductor layer 310, and is electrically separated from the firstelectrode layer 360, the first-conductivity type semiconductor layer330, and the active layer 320. The electrode connection portion 350-c isformed on the same layer as the first electrode layer 360, but iselectrically separated from the first electrode layer 360. The electrodeconnection portion 350-c connects the electrode pad portion 350-b to theelectrode extension portion 350-a.

The conductive substrate 340 may be a metal substrate, a semiconductorsubstrate, or a combination thereof. When the conductive substrate 340is a metal substrate, it may be formed of any one of Au, Ni, Cu, Al, andW. When the conductive substrate 340 is a semiconductor substrate, itmay be formed of any one of Si, Ge, and GaAs. Also, the conductivesubstrate 340 may be formed of a material including Au, Ni, Al, Cu, W,Si, Se, and GaAs, for example, SiAl, which is a combination of Si andAl. The conductive substrate 340 is formed in the semiconductor lightemitting device by a plating method, which forms a substrate by forminga plating seed layer, or a substrate bonding method, which separatelyprepares the conductive substrate 340 and attaches it using a conductiveadhesive, e.g., Au, Sn, Ni, Au—Sn, Ni—Sn, Ni—Au—Sn, Pb—Sr, etc.

The semiconductor layers 330 and 310 may be formed of an inorganicsemiconductor material, e.g., a GaN-based semiconductor, a SiC-basedsemiconductor, a ZnO-based semiconductor, a GaAs-based semiconductor, aGaP-based semiconductor, a GaAsP-based semiconductor, etc. Thesemiconductor layers 330 and 310 may be formed using a metal organicchemical vapor deposition (MOCVD) method, or a molecular beam epitaxy(MBE) method. Furthermore, the semiconductor layers 330 and 310 may beformed of a material selected from the group consisting of a group III-Vsemiconductor, a group IV-IV semiconductor, a group II-VI semiconductor,a group IV semiconductor, such as Si, and combinations thereof.

The active layer 320 is a layer which activates light emission, and isformed of a material having a smaller energy band gap than those of thefirst-conductivity type semiconductor layer 330 and thesecond-conductivity type semiconductor layer 310. For example, when thefirst-conductivity type semiconductor layer 330 and thesecond-conductivity type semiconductor layer 310 are formed of aGaN-based compound semiconductor, the active layer 320 may be formed ofan InAlGaN-based compound semiconductor having a smaller energy band gapthan that of GaN. That is, the active layer 320 may includeIn_(x)Al_(y)Ga_((1-x-y))N (where 0≦x≦1, 0≦y≦1, 0≦x+y≦1).

The wavelength of the emitted light may be adjusted by controlling amole ratio of the constituent materials of the active layer 320.Therefore, the semiconductor light emitting device 300 may emit infraredlight, visible light, or ultraviolet light according to characteristicsof the active layer 320.

An energy well structure appears in the entire energy band diagram ofthe semiconductor light emitting device 300 according to the activelayer 320, and electrons and holes from the respective semiconductorlayers 330 and 310 are confined in the energy well structure, therebyimproving light emission.

The first electrode layer 360 is an electrode which electricallyconnects the first-conductivity type semiconductor layer 330 to anexternal power source (not shown). The first electrode layer 360 may beformed of a metal. For example, the first electrode layer 360 formed asan n-type electrode may be formed of Ti, Al, Cr, or Au, and the firstelectrode layer 360 formed as a p-type electrode may be formed of Ni,Pd, Ag, Al, Pt, or Au.

The first electrode layer 360 reflects light generated from the activelayer 320. The reflected light is directed to a light emitting plane,thus increasing the luminous efficiency of the semiconductor lightemitting device 300. In order to reflect the light generated from theactive layer 320, the first electrode layer 360 may be formed of a metalwhich is whitish in the visible light range. For example, the firstelectrode layer 360 may be formed of any one of Ag, Al, and Pt. Thefirst electrode layer 360 will be described later in more detail withreference to FIGS. 12A through 12C.

The second electrode part 350 is an electrode which electricallyconnects the second-conductivity type semiconductor layer 310 to anexternal power source (not shown). The second electrode part 350 may beformed of a metal. The second electrode part 350 formed as an n-typeelectrode may be formed of Ti, and the second electrode part 350 formedas a p-type electrode may be formed of Pd or Au. Specifically, thesecond electrode part 350 according to this embodiment of the presentinvention includes the electrode pad portion 350-b, the electrodeextension portion 350-a and the electrode connection portion 350-c.

Referring to FIG. 11A, the electrode pad portion 350-b is formed on thesecond-conductivity type semiconductor layer 310, and a plurality ofelectrode extension portions 350-a indicated by a dotted line aredisposed within the second-conductivity type semiconductor layer 310.

FIG. 11B illustrates the sections of the top surface of thesecond-conductivity type semiconductor layer 310 of FIG. 11A, takenalong lines A-A, B-B′ and C-C′. The line A-A′ is selected to take in thesection which includes the electrode extension portion 350-a only, andthe line B-B′ is selected to take in the section which includes theelectrode pad portion 350-b and the electrode extension portion 350-a.The line C-C′ is selected to take in the section which does not includethe electrode extension portion 350-a and the electrode pad portion350-b.

FIGS. 12A through 12C are cross-sectional views of the semiconductorlight emitting device of FIG. 11B, taken along the lines A-A′, B-B′ andC-C′, respectively. The semiconductor light emitting device will bedescribed below with reference to FIGS. 10, 11A, 11B and 12A through12C.

Referring to FIG. 12A, the electrode extension portion 350-a extendsfrom the first electrode layer 360 to the inside of thesecond-conductivity type semiconductor layer 310. The electrodeextension portion 350-a passes through the first-conductivity typesemiconductor layer 330 and the active layer 320 and extends to thesecond-conductivity type semiconductor layer 310. The electrodeextension portion 350-a extends to a portion of at least thesecond-conductivity type semiconductor layer 310, but need not extend tothe surface of the second-conductivity type semiconductor layer 310, asopposed to the electrode pad portion 350-b. This is because theelectrode extension portion 350-a is formed for dispersing the currentto the second-conductivity type semiconductor layer 310.

The electrode extension portion 350-a must have a predetermined areabecause it is formed for dispersing the current to thesecond-conductivity type semiconductor layer 310. However, unlike theelectrode pad portion 350-b, the electrode extension portion 350-a isnot used for electrical connection, and thus, a predetermined number ofthe electrode extension portions 350-a may be formed in such a smallarea that current may be uniformly dispersed on the second-conductivitytype semiconductor layer 310. If a very small number of the electrodeextension portions 350-a are formed, current dispersion is difficult andthe electrical characteristics are degraded. If a very large number ofthe electrode extension portions 350-a are formed, the fabricationprocess is difficult and the active layer is reduced, causing areduction in the light emitting area. Thus, the number of the electrodeextension portions 350-a may be appropriately selected, taking intoconsideration those conditions. Therefore, the electrode extensionportions 350-a are implemented in a shape which occupies an area assmall as possible and is effective in the current dispersion.

The electrode extension portions 350-a may be provided in plurality inorder to facilitate current dispersion. In addition, the electrodeextension portion 350-a may have a cylindrical shape and may have asmaller area than the electrode pad portion 350-b. The electrodeextension portion 350-a may be formed to be spaced apart from theelectrode pad portion 350-b by a predetermined distance. Since theelectrode extension portion 350-a may be connected to the electrode padportion 350-b on the first electrode layer 360 by the electrodeconnection portion 350-c, which will be described later, uniform currentdispersion is obtained by spacing the electrode extension portion 350-aapart from the electrode pad portion 350-b by a predetermined distance.

The electrode extension portion 350-a is formed from the first electrodelayer 360 to the inside of the second-conductivity type semiconductorlayer 310. Since the electrode extension portion 350-a is formed for thecurrent dispersion of the second-conductivity type semiconductor layer310, the electrode extension portion 350-a needs to be electricallyseparated from the other layers. Hence, the electrode extension portion350-a is electrically separated from the first electrode layer 360, thefirst-conductivity type semiconductor layer 330, and the active layer320. The electrical separation may be performed using an insulatingmaterial such as a dielectric.

Referring to FIG. 12B, the electrode pad portion 350-b extends from thefirst electrode layer 360 to the surface of the second-conductivity typesemiconductor layer 310. The electrode pad portion 350-b extends fromthe first electrode layer 360 to the surface of the second-conductivitytype semiconductor layer 310, while passing through thefirst-conductivity type semiconductor layer 330, the active layer 320,and the second-conductivity type semiconductor layer 310. In particular,the electrode pad portion 350-b is formed for electrical connectionbetween the second electrode part 350 and an external power source (notshown). Therefore, the second electrode part 350 may include at leastone electrode pad portion 350-b.

The electrode pad portion 350-b extends from the first electrode layer360 to the surface of the second-conductivity type semiconductor layer310. The electrode pad portion 350-b is electrically connected to theexternal power source on the second-conductivity type semiconductorlayer 310 and supplies a current to the electrode extension portion350-a. Thus, the electrode pad portion 350-b may be electricallyseparated from the first electrode layer 360, the first-conductivitytype semiconductor layer 330, and the active layer 320. The electricalseparation may be performed by forming an insulation layer using aninsulating material such as a dielectric.

The electrode pad portion 350-b may supply a current to the electrodeextension portion 350-a, and may directly disperse a current because itis not electrically separated from the second-conductivity typesemiconductor layer 310. The electrode pad portion 350-b may beappropriately electrically separated from the second-conductivity typesemiconductor layer 310, taking into consideration the required one ofthe two functions, that is, the function of supplying a current to theelectrode extension portion 350-a and the function of dispersing acurrent to the second-conductivity type semiconductor layer 310.

Specifically, in the electrode pad portion 350-b, the section on theactive layer 320 may have a smaller area than the section on the surfaceof the second-conductivity type semiconductor layer 310 in order tomaximize the active layer 320 and increase the luminous efficiency ofthe semiconductor light emitting device 300. However, the section on thesecond-conductivity type semiconductor layer 310 needs to have apredetermined area in order for connection to the external power source(not shown).

The electrode pad portions 350-b may be disposed at the center of thesemiconductor light emitting device 300. In this case, the electrodeextension portions 350-a may be uniformly dispersed and spaced apartfrom the electrode pad portion 350-b by a predetermined distance.Referring to FIG. 11A, the electrode pad portion 350-b and the electrodeextension portion 350-a are uniformly dispersed on thesecond-conductivity type semiconductor layer 310, thereby optimizingcurrent dispersion. In FIG. 11A, it is assumed that the number of theelectrode pad portions 350-b is 1 and the number of the electrodeextension portions 350-a is 12. However, the number of the electrode padportions 350-b and the number of the electrode extension portions 350-amay be appropriately selected, taking into consideration the currentdispersion conditions, such as the electrical connection state (e.g.,the position of the external power source), the thickness of thesecond-conductivity type semiconductor layer 310, and so on.

When a plurality of electrode extension portions 350-a are provided, theelectrode pad portion 350-b and the plurality of electrode extensionportions 350-a may be directly connected together. In this case, theelectrode pad portion 350-b may be formed at the center of thesemiconductor light emitting device 300, and the electrode extensionportions 350-a may be disposed surrounding the electrode pad portion350-b. The electrode connection portion 350-c may directly connect theelectrode pad portion 350-b to the electrode extension portions 350-a ina radial form.

Alternatively, some of the electrode extension portions 350-a may bedirectly connected to the electrode pad portion 350-b, and the remainingelectrode extension portions 350-a may be indirectly connected to theelectrode pad portion 350-b in a manner such that they are connected tothe electrode extension portions 350-a directly connected to theelectrode pad portion 350-b. In this case, the efficiency of the currentdispersion is improved because a larger number of the electrodeextension portions 350-a can be formed.

Referring to FIGS. 12A through 12C, the electrode connection portion350-c is formed on the first electrode layer 360 to connect theelectrode pad portion 350-b to the electrode extension portions 350-a.Therefore, a considerable portion of the second electrode part 350 isdisposed at the rear source of the active layer 320, that is, a surfaceopposite to the direction in which light is traveling, therebyincreasing the luminous efficiency of the semiconductor light emittingdevice. Specifically, in FIG. 12C, the electrode connection portion350-c only is disposed on the first electrode layer 360, and the secondelectrode part 350 is not disposed on the first-conductivity typesemiconductor layer 330, the active layer 320, and thesecond-conductivity type semiconductor layer 310. Hence, in the case ofFIG. 12C, the electrode pad portion 350-b and the electrode extensionportions 350-a do not influence light emission and thus become an areawhich increases luminous efficiency. Although not illustrated in FIG.12C, the first electrode layer 360 may come into contact with theconductive substrate 340 and be connected to the external power source(not shown).

The electrode connection portion 350-c is electrically separated fromthe first electrode layer 360. The first electrode layer 360 and thesecond electrode part 350 have opposite polarity. Since the firstelectrode layer 360 and the second electrode part 350 supply theexternal power to the first-conductivity type semiconductor layer 330and the second-conductivity type semiconductor layer 310, the electrodesmust be electrically separated from each other. The electricalseparation may be performed using an insulating material such as adielectric.

In FIG. 12B, since the electrode pad portion 350-b is disposed on thesurface of the second-conductivity type semiconductor layer 310, acharacteristic of a vertical type semiconductor light emitting devicemay be exhibited. In FIG. 12C, since the electrode connection portion350-c is disposed on the same plane as the first electrode layer, acharacteristic of a horizontal type semiconductor light emitting devicemay be exhibited. Therefore, the semiconductor light emitting device hasa hybrid type structure having both the horizontal type and the verticaltype.

In FIGS. 12A through 12C, the second-conductivity type semiconductorlayer 310 may be an n-type semiconductor layer, and the second electrodepart may be an n-type electrode part. In this case, thefirst-conductivity type semiconductor layer 330 may be a p-typesemiconductor layer, and the first electrode layer 360 may be a p-typeelectrode. The electrode pad portion 350-b, the electrode extensionportion 350-a, and the electrode connection portion 350-c are connectedtogether to form the second electrode part 350. When the secondelectrode part 350 is an n-type electrode, the second electrode part 350may be electrically separated from the first electrode layer 360, whichis the p-type electrode, by forming the insulation layer 370 using aninsulating material.

FIG. 13A illustrates the light emission of a semiconductor lightemitting device having an uneven pattern 380 on the surface thereofaccording to a modified embodiment of the present invention, and FIG.13B illustrates the current dispersion of a semiconductor light emittingdevice having an uneven pattern 380 on the surface thereof according toanother modified embodiment of the present invention.

In the semiconductor light emitting device 300 according to thisembodiment of the present invention, the outermost surface in the lighttraveling direction is formed of the second-conductivity typesemiconductor layer 310. Therefore, the uneven pattern 380 on thesurface of the semiconductor light emitting device may be formed using aknown method such as lithography. In this case, the light emitted fromthe active layer 320 is extracted while passing through the unevenpattern 380 formed on the surface of the second-conductivity typesemiconductor layer 310. Thus, light extraction efficiency is increasedby the uneven pattern 380.

The uneven pattern 380 may have a photonic crystal structure. A photoniccrystal structure is a structure in which media having differentrefractive indexes are arranged regularly in a crystal-like manner. Thephotonic crystal structure may further increase light extractionefficiency because it can adjust light on the basis of a length unitcorresponding to the multiple of the wavelength of light. The photoniccrystal structure may be manufactured by forming the second-conductivitytype semiconductor layer 310 and the second electrode part 350 andperforming a predetermined process. For example, the photonic crystalstructure may be formed by an etching process.

Even though the uneven pattern 380 is formed on the second-conductivitytype semiconductor layer 310, there is no influence on the currentdispersion. Referring to FIG. 13B, the current dispersion in theelectrode extension portion 350-a is not affected by the uneven pattern380. The respective electrode extension portions 350-a disperse thecurrent at a position under the uneven pattern 380, and the unevenpattern 380 extracts the emitted light, thereby increasing luminousefficiency.

FIG. 14 is a graph showing the relationship between the current densityof the light emitting plane and the luminous efficiency. Referring toFIG. 14, in a case in which the current density is approximately 10A/cm² or more, the luminous efficiency is high when the current densityis low, and the luminous efficiency is low when the current density ishigh.

Those values are listed in Table 1 below.

TABLE 1 Light Current Luminous emitting area density efficiencyImprovement (cm²) (A/cm²) (lm/W) rate (%) 0.0056 62.5 46.9 100 0.007050.0 51.5 110 0.0075 46.7 52.9 113 0.0080 43.8 54.1 115

As the light emitting area increases, the luminous efficiency increases.However, since the area of the distributed electrodes must be reduced inorder to ensure the light emitting area, the current density of thelight emitting plane tends to be reduced. The reduction of currentdensity in the light emitting plane may degrade the electricalcharacteristics of the semiconductor light emitting device.

However, such a problem may be solved by ensuring current dispersionusing the electrode extension portion. Therefore, the problem ofelectrical characteristics, which may be caused by reduced currentdensity, can be solved by forming the electrode extension portion whichmanages the current dispersion. At this time, the electrode extensionportion is formed inside, instead of forming the light emitting surface.Therefore, the semiconductor light emitting device according to thisembodiment of the present invention can obtain the desired currentdispersion degree and the maximum light emitting area, thereby acquiringthe desired luminous efficiency.

FIGS. 15 through 18 illustrate a semiconductor light emitting deviceaccording to another embodiment of the present invention.

FIG. 15 is a cross-sectional view of a semiconductor light emittingdevice according to another embodiment of the present invention, FIGS.16A and 16B are top views of the semiconductor light emitting deviceillustrated in FIG. 15, and FIGS. 17A through 17C are cross-sectionalviews of the semiconductor light emitting device illustrated in FIG.16B, taken along lines A-A′, B-B′ and C-C′, respectively.

The semiconductor light emitting device 400 according to anotherembodiment of the present invention includes: a light emitting stackstructure 430, 420 and 410 provided with a first-conductivity typesemiconductor layer 430, a second-conductivity type semiconductor layer410, and an active layer 420 formed between the first-conductivity typesemiconductor layer 430 and the second-conductivity type semiconductorlayer 410, wherein the first-conductivity type semiconductor layer 430and the second-conductivity type semiconductor layer 410 are provided asa first plane and a second plane of the light emitting stack structure430, 420 and 410, which face each other; at least one electricallyinsulating barrier rib part 470 extending from the second plane of thelight emitting stack structure 430, 420 and 410 to a portion of at leastthe second-conductivity type semiconductor layer 410 so that the lightemitting stack structure 430, 420 and 410 is separated into a pluralityof light emitting regions; a second electrode structure 460 formed to beconnected to the second-conductivity type semiconductor layer 410disposed in the plurality of light emitting regions; a first electrodestructure 440 formed on the second plane of the light emitting stackstructure 430, 420 and 410 so that the first electrode structure 440 isconnected to the first-conductivity type semiconductor layer 430; and aconductive substrate 450 formed on the second plane of the lightemitting stack structure 430, 420 and 410 so that the conductivesubstrate 450 is electrically connected to the first electrode structure440.

The light emitting stack structure 430, 420 and 410 includes thefirst-conductivity type semiconductor layer 430, the second-conductivitytype semiconductor layer 410, and the active layer 420 formed betweenthe first-conductivity type semiconductor layer 430 and thesecond-conductivity type semiconductor layer 410. The outer surface ofthe second-conductivity type semiconductor layer 410 is provided as thefirst plane of the light emitting stack structure 430, 420 and 410, andthe outer surface of the first-conductivity type semiconductor layer 410is provided as the second plane of the light emitting stack structure430, 420 and 410.

For example, the semiconductor layers 430 and 410 may be formed ofsemiconductors, such as GaN-based semiconductors, SiC-basedsemiconductors, ZnO-based semiconductors, GaAs-based semiconductors,GaP-based semiconductors, or GaAsP-based semiconductors. The formationof the semiconductor layers 430 and 410 may be performed using a metalorganic chemical vapor deposition (MOCVD) process or a molecular beamepitaxy (MBE) process. Alternatively, the semiconductor layers 430 and410 may be formed of a material selected from the group consisting ofgroup III-V semiconductors, group IV-IV semiconductors, group II-VIsemiconductors, group IV semiconductors such as Si, and combinationsthereof. The light emitting stack structure may be grown on a SiCsubstrate (not shown), an Si substrate (not shown), or a GaAs substrate(not shown). The substrate (not shown) is removed before a subsequentbonding of the conductive substrate.

The active layer 420 is a layer which activates light emission. Theactive layer 420 is formed of a material having a smaller energy bandgap than the second-conductivity type semiconductor layer 410 and thefirst-conductivity type semiconductor layer 430. For example, when thesecond-conductivity type semiconductor layer 410 and thefirst-conductivity type semiconductor layer 430 are formed of GaN-basedsemiconductors, the active layer 420 may be formed of InAlGaN-basedsemiconductors having a smaller energy band gap than the GaN-basedsemiconductors. That is, the active layer 420 may includeIn_(x)Al_(y)Ga_((1-x-y))N (where 0≦x≦1, 0≦y≦1, and 0≦x+y≦1).

The wavelength of the emitted light may be adjusted by controlling amole ratio of the constituent materials of the active layer 420.Therefore, the semiconductor light emitting device 400 may emit infraredlight, visible light, or ultraviolet light according to thecharacteristics of the active layer 420.

An energy well structure appears in the entire energy band diagram ofthe semiconductor light emitting device 400 according to the activelayer 420, and electrons and holes from the respective semiconductorlayers 430 and 410 are confined in the energy well structure, therebyimproving light emission.

The barrier rib part 470 extends from the second plane of the lightemitting stack structure 430, 420 and 410 to a portion of at least thesecond-conductivity type semiconductor layer 410 so that the lightemitting stack structure 430, 420 and 410 is separated into a pluralityof light emitting regions. The barrier rib part 470 separates thesecond-conductivity type semiconductor layer 410 into a plurality oflight emitting regions and reduces stress caused by heat energy appliedto the interface when a separating tool such as a laser is appliedbetween the second-conductivity type semiconductor layer 410 and agrowth substrate (not shown) formed on the second-conductivity typesemiconductor layer 410.

For example, when the laser is used for separating thesecond-conductivity type semiconductor layer 410 from the growthsubstrate (not shown), the temperature at the interface is approximately1,000° C. Therefore, the second-conductivity type semiconductor layer410 is separated from the growth substrate (not shown), but the heatcauses a stress which induces contraction and expansion in thesemiconductor layers and the conductive substrate 450 to be subsequentlyattached thereto. Generally, since the magnitude of the stress isproportional to the area, such stress may adversely affect thelarge-sized semiconductor light emitting device.

However, since the semiconductor light emitting device 400 according tothis embodiment of the present invention includes the barrier rib part470, the area of the second-conductivity type semiconductor layer 410 isreduced to the area of the plurality of light emitting regions, therebyreducing stress. That is, since expansion and contraction easily occurin the plurality of light emitting regions, the light emission of thelight emitting stack structure 430, 420 and 410 is stabilized.

The barrier rib part 470 electrically insulates the semiconductor layers430 and 410 and the active layer 420. To this end, the barrier rib part470 may be filled with air. Alternatively, an insulation layer may beformed inside the barrier rib part 470, and the inside of the insulationlayer may be filled with air. Furthermore, the electrical insulation maybe achieved by filling the entire inside of the barrier rib part 470with an insulating material such as a dielectric.

In order to electrically insulate the light emitting stack structure430, 420 and 410, the barrier rib part 470 may extend from the secondplane to the top surface of the second-conductivity type semiconductorlayer 410. However, the barrier rib part 470 does not necessarily extendto the top surface of the second-conductivity type semiconductor layer410. For example, the barrier rib part 470 may extend to the inside ofthe second-conductivity type semiconductor layer 410.

Moreover, the barrier rib part 470 may be formed in a single structure,or may include a plurality of barrier ribs separated from one another.In this case, the plurality of barrier ribs may be differently formed togive necessary electrical characteristics. For example, the barrier ribpart surrounding a bonding part 461 and the barrier rib part surroundinga contact hole 462 may be different in height or shape.

The second electrode structure 460 is formed to be connected to thesecond-conductivity type semiconductor layer 410 disposed in theplurality of light emitting regions separated by the barrier rib part470. The second electrode structure 460 includes a contact hole 462, abonding part 461, and an interconnection part 463.

The contact hole 462 may be provided in plurality. A single contact hole462 may be provided in a single light emitting region, or a plurality ofcontact holes 462 may be provided in a single light emitting region. Thecontact hole 462 is formed to be electrically connected to thesecond-conductivity type semiconductor layer 410 and electricallyinsulated from the first-conductivity type semiconductor layer 430 andthe active layer 420. To this end, the contact hole 462 extends from thesecond plane of the light emitting stack structure 430, 420 and 410 toat least a portion of the second-conductivity type semiconductor layer410. The contact hole 462 is formed to disperse the current on thesecond-conductivity type semiconductor layer 410.

The bonding part 461 is formed to be connected from the first plane ofthe light emitting stack structure 430, 420 and 410 to at least one ofthe plurality of contact holes 462, and the region exposed in the firstplane is provided as the bonding region.

The interconnection part 463 is provided in the second plane of thelight emitting stack structure 430, 420 and 410 and electricallyinsulated from at least the first-conductivity type semiconductor layer430, so that the contact hole 462 connected to the bonding part 461 iselectrically connected to the other contact hole 462. Theinterconnection part 463 may electrically connect the contact hole 462to the other contact hole 462 and electrically connect the contact hole462 to the bonding part 461. The luminous efficiency may be improved bydisposing the interconnection part 463 under the second-conductivitytype semiconductor layer 410 and the active layer 420.

Hereinafter, the contact hole 462, the bonding part 461, and theinterconnection part 463 will be described in more detail with referenceto FIGS. 16C through 17C.

The first electrode structure 440 is formed on the second plane of thelight emitting stack structure 430, 420 and 410 so that the firstelectrode structure 440 is electrically connected to thefirst-conductivity type semiconductor layer 430. That is, the firstelectrode structure 440 is an electrode which electrically connects thefirst-conductivity type semiconductor layer 430 to an external powersource (not shown). The first electrode structure 440 may be formed of ametal. For example, the first electrode structure 440 as an n-typeelectrode may be formed of Ti, Al, Cr, or Au, and the first electrodestructure 440 as a p-type electrode may be formed of Ni, Pd, Ag, Al, Pt,or Au.

The first electrode structure 440 reflects light emitted from the activelayer 420. Since the first electrode structure 440 is disposed under theactive layer 420, it is disposed on a plane opposite to the lightemitting direction of the semiconductor light emitting device withrespect to the active layer 420. Therefore, light traveling from theactive layer 420 to the first electrode structure 440 travels in adirection opposite to the light emitting direction. Thus, in order toincrease the luminous efficiency, such light must be reflected.Consequently, the light reflected from the first electrode structure 440is directed to the light emitting plane, thereby increasing the luminousefficiency of the semiconductor light emitting device.

In order to reflect the light emitted from the active layer 420, thefirst electrode structure 440 may be formed of a metal which is whitishin a visible light range. For example, the first electrode structure 440may be formed of any one of Ag, Al, and Pt. The first electrodestructure 440 will be described later in more detail with reference toFIGS. 17A through 17C.

The conductive substrate 450 is formed on the second plane of the lightemitting stack structure 430, 420 and 410 so that the conductivesubstrate 450 is electrically connected to the first electrode structure440. The conductive substrate 450 may be a metal substrate or asemiconductor substrate. When the conductive substrate 450 is a metalsubstrate, it may be formed of any one of Au, Ni, Cu, and W. When theconductive substrate 450 is a semiconductor substrate, it may be formedof any one of Si, Ge, and GaAs. Also, the conductive substrate 450 maybe formed of a material including Au, Ni, Al, Cu, W, Si, Se, and GaAs,for example, SiAl, which is a combination of Si and Al. The conductivesubstrate 450 is formed in the semiconductor light emitting device by aplating method, which forms a substrate by forming a plating seed layer,or a substrate bonding method, which separately prepares the conductivesubstrate 450 and attaches it by using a conductive adhesive, e.g., Au,Sn, Ni, Au—Sn, Ni—Sn, Ni—Au—Sn, Pb—Sr, etc.

Referring to FIG. 16A, the bonding part 461 is formed on thesecond-conductivity type semiconductor layer 410, and the plurality ofcontact holes 462 indicated by dotted lines are disposed inside thesecond-conductivity type semiconductor layer 410. Thesecond-conductivity type semiconductor layer 410 includes a plurality oflight emitting regions separated by the barrier rib part 470. Althoughone bonding part 461 is illustrated in FIGS. 16A and 16B, a plurality ofbonding parts 461 may be formed in the same light emitting region, or aplurality of bonding parts 461 may be formed in a plurality of lightemitting regions. Also, although one contact hole 462 is formed in eachlight emitting region, the current dispersion may be further improved byforming a plurality of contact holes 462 in a single light emittingregion.

FIG. 16B illustrates the sections of the top surface of thesecond-conductivity type semiconductor layer 410 of FIG. 16A, takenalong lines A-A, B-B′ and C-C′. The line A-A′ is selected to take in thesection which includes the contact hole 462 only, and the line B-B′ isselected to take in the section which includes the bonding part 461 andthe contact hole 462. The line C-C′ is selected to take in the sectionwhich does not include the contact hole 462 and the bonding part 461,but includes the interconnection part 463 only.

FIGS. 17A through 17C are cross-sectional views of the semiconductorlight emitting device of FIG. 16B, taken along the lines A-A′, B-B′ andC-C′, respectively. The semiconductor light emitting device will bedescribed below with reference to FIGS. 15, 16A, 16B and 17A through17C.

Referring to FIG. 17A, the contact hole 462 extends from the firstelectrode structure 440 to the inside of the second-conductivity typesemiconductor layer 410. The contact hole 462 passes through thefirst-conductivity type semiconductor layer 430 and the active layer 420and extends to the second-conductivity type semiconductor layer 410. Thecontact hole 462 extends up to a portion of at least thesecond-conductivity type semiconductor layer 410, but need not extend tothe surface of the second-conductivity type semiconductor layer 410, asopposed to the bonding part 461. However, the contact hole 462 mustextend to the second-conductivity type semiconductor layer 410 becausethe contact hole 462 is formed for dispersing the current to thesecond-conductivity type semiconductor layer 410.

The contact hole 462 must have a predetermined area because it is formedfor dispersing the current to the second-conductivity type semiconductorlayer 410. However, unlike the bonding part 461, the contact hole 462 isnot used for electrical connection, and thus, a predetermined number ofcontact holes 462 may be formed in such a small area that the currentmay be uniformly dispersed on the second-conductivity type semiconductorlayer 410. If a very small number of contact holes 462 are formed,current dispersion is difficult and the electrical characteristics aredegraded. If a very large number of the contact holes 462 are formed,the fabrication process is difficult and the active layer is reduced,causing a reduction in the light emitting area. Thus, the number ofcontact holes 462 may be appropriately selected, taking intoconsideration those conditions. Therefore, the contact holes 462 areimplemented in a shape which occupies an area as small as possible andis effective in the current dispersion.

The contact hole 462 may be provided in plurality in order for thecurrent dispersion. In addition, the contact hole 462 may have acylindrical shape and may have a smaller sectional area than the bondingpart 461. The contact hole 462 may be formed to be spaced apart from thebonding part 461 by a predetermined distance. Since the contact hole 462may be connected to the bonding part 461 on the first electrodestructure 440 by the interconnection part 463, which will be describedlater, uniform current dispersion must be induced within thesecond-conductivity type semiconductor layer 410 by spacing the contacthole 462 apart from the bonding part 461 by a predetermined distance.

The contact hole 462 is formed from the first electrode structure 440 tothe inside of the second-conductivity type semiconductor layer 410.Since the contact hole 462 is formed for the current dispersion of thesecond-conductivity type semiconductor layer 410, the contact hole 462needs to be electrically separated from the first-conductivity typesemiconductor layer 430 and the active layer 420. Hence, the contacthole 462 is electrically separated from the first electrode structure440, the first-conductivity type semiconductor layer 430, and the activelayer 220. The electrical separation may be performed using aninsulating material such as a dielectric.

Referring to FIG. 17B, the bonding part 461 extends from the firstelectrode structure 440 to the surface of the second-conductivity typesemiconductor layer 410, while passing through the first-conductivitytype semiconductor layer 430, the active layer 420, and thesecond-conductivity type semiconductor layer 410. The bonding part 461is formed to be connected from the first plane of the light emittingstack structure 430, 420 and 410 to at least one of the contact holes462. The region exposed to the first plane is provided as the bondingregion.

In particular, the bonding part 461 is formed for electrical connectionbetween the second electrode structure 460 and the external power source(not shown). Therefore, the second electrode structure 460 may includeat least one bonding part 461.

The bonding part 461 is electrically connected to the external powersource on the surface of the second-conductivity type semiconductorlayer 410 and supplies a current to the contact hole 462. Thus, thebonding part 461 may be electrically separated from the first electrode440, the second-conductivity type semiconductor layer 410, and theactive layer 420. The electrical separation may be performed by formingan insulation layer using an insulating material such as a dielectric.

The bonding part 461 functions to supply a current to the contact hole462, and may directly disperse a current because it is not electricallyseparated from the second-conductivity type semiconductor layer 410. Thebonding part 461 may be appropriately electrically separated from thesecond-conductivity type semiconductor layer 410, taking intoconsideration the required function, that is, either the function ofsupplying a current to the contact hole 462 or the function ofdispersing a current to the second-conductivity type semiconductor layer410.

Specifically, in the bonding part 461, the section on the active layer420 may have a smaller area than the section on the surface of thesecond-conductivity type semiconductor layer 410 in order to maximizethe active layer 420 and increase the luminous efficiency of thesemiconductor light emitting device 400. However, the section on thesecond-conductivity type semiconductor layer 410 needs to have apredetermined area in order for connection to the external power source(not shown).

The bonding part 461 may be disposed at the center of the semiconductorlight emitting device 400. In this case, the contact hole 462 may beuniformly dispersed and spaced apart from the bonding part 461 by apredetermined distance. Referring again to FIG. 16A, the bonding part461 and the contact hole 462 are uniformly dispersed on thesecond-conductivity type semiconductor layer 410, thereby optimizing thecurrent dispersion. In FIG. 16A, it is assumed that the number of thebonding parts 461 is 1 and the number of the contact holes 462 is 8.However, the number of the bonding parts 461 and the number of thecontact holes 462 may be appropriately selected, taking intoconsideration the current dispersion conditions, such as the electricalconnection state (e.g., the position of the external power source), thethickness of the second-conductivity type semiconductor layer 410, andso on.

When a plurality of contact holes 462 are provided, the bonding part 461and the plurality of contact holes 462 may be directly connectedtogether. In this case, the bonding part 462 may be formed at the centerof the semiconductor light emitting device 400, and the contact holes462 may be disposed surrounding the bonding part 461. Theinterconnection part 463 may directly connect the bonding part 461 tothe contact holes 462 in a radial form.

Alternatively, some of the contact holes 462 may be directly connectedto the bonding part 461, and the remaining contact holes 462 may beindirectly connected to the bonding part 461 in a manner such that theyare connected to the contact holes 462 directly connected to the bondingpart 461. In this case, the efficiency of the current dispersion isimproved because a larger number of the contact holes 462 can be formed.

Referring to FIGS. 17A through 17C, the interconnection part 463 isformed on the first electrode structure 440 to connect the bonding part461 to the contact hole 462. Therefore, a considerable portion of thefirst electrode structure 440 is disposed at the rear source of theactive layer 420, that is, a surface opposite to the traveling directionof the light, thereby increasing the luminous efficiency of thesemiconductor light emitting device 400. Specifically, in FIG. 17C, theinterconnection part 463 is only disposed on the first electrodestructure 440, and the second electrode structure 460 is not disposed onthe first-conductivity type semiconductor layer 430, the active layer420, and the second-conductivity type semiconductor layer 410. Hence, inthe case of FIG. 17C, the bonding part 461 and the contact holes 462 donot influence the light emission and thus become an area which increasesluminous efficiency.

The interconnection part 463 is electrically separated from the firstelectrode structure 440. The second electrode structure 460 and thefirst electrode structure 440 have opposite polarity. Since the secondelectrode structure 460 and the first electrode structure 440 supply theexternal power to the second-conductivity type semiconductor layer 410and the first-conductivity type semiconductor layer 430, the twoelectrodes must be electrically separated from each other. Theelectrical separation may be performed by forming the insulation layer480 using an insulating material such as a dielectric.

In FIG. 17B, since the bonding part 461 is disposed on the surface ofthe second-conductivity type semiconductor layer 410, it may have thecharacteristics of a vertical type semiconductor light emitting device.In FIG. 17C, since the interconnection part 463 is disposed on the sameplane as the first electrode structure 440, it may have thecharacteristics of a horizontal type semiconductor light emittingdevice. Therefore, the semiconductor light emitting device 400 has ahybrid type structure having the characteristics of both the horizontaltype and the vertical type semiconductor light emitting devices.

In FIGS. 17A through 17C, the first-conductivity type semiconductorlayer 430 may be a p-type semiconductor layer, and the first electrodestructure 440 may be a p-type electrode part. In this case, thesecond-conductivity type semiconductor layer 410 may be an n-typesemiconductor layer, and the second electrode structure 460 may be ann-type electrode. The bonding part 461, the contact hole 462, and theinterconnection part 463 are connected together to form the secondelectrode structure 460. When the second electrode structure 460 is ann-type electrode, the second electrode structure 460 may be electricallyseparated from the first electrode structure 440, which is the p-typeelectrode, by forming the insulation layer 480 using an insulatingmaterial.

FIG. 18 illustrates the light emission of a semiconductor light emittingdevice having an uneven pattern on the surface thereof according to anembodiment of the present invention. In the semiconductor light emittingdevice according to this embodiment of the present invention, theoutermost surface in the light traveling direction is formed of thesecond-conductivity type semiconductor layer 410. Therefore, the unevenpattern 490 on the surface of the semiconductor light emitting devicemay be formed using a known method such as lithography. In this case,the light emitted from the active layer 420 is extracted while passingthrough the uneven pattern 490 formed on the surface of thesecond-conductivity type semiconductor layer 410. Thus, the lightextraction efficiency is increased by the uneven pattern 490.

The uneven pattern 490 may have a photonic crystal structure. A photoniccrystal structure refers to a structure in which media having differentrefractive indexes are arranged regularly in a crystal-like manner. Thephotonic crystal structure may further increase the light extractionefficiency because it can adjust light on the basis of length unitcorresponding to the multiple of the wavelength of light. The photoniccrystal structure may be manufactured by forming the second-conductivitytype semiconductor layer 410 and the first electrode structure 460 andperforming a predetermined process. For example, the photonic crystalstructure may be formed by an etching process.

When the uneven pattern 490 is formed on the second-conductivity typesemiconductor layer 410, the barrier rib part 470 may be formed up tothe inside of the second-conductivity type semiconductor layer 410, notto the surface of the second-conductivity type semiconductor layer 410.The barrier rib part 470 functions to separate the light emitting regioninto a plurality of sub light emitting regions, while not badlyaffecting the light extraction efficiency improvement performance of theuneven pattern 490.

A semiconductor light emitting device according to another embodiment ofthe present invention will be described below with reference to FIGS. 19through 23.

FIG. 19 is a perspective view of a semiconductor light emitting deviceaccording to another embodiment of the present invention, and FIG. 20 isa plan view of the semiconductor light emitting device illustrated inFIG. 19. The semiconductor light emitting device will be described belowwith reference to FIGS. 19 and 20.

The semiconductor light emitting device 500 according to this embodimentof the present invention includes a first-conductivity typesemiconductor layer 511, an active layer 512, a second-conductivity typesemiconductor layer 513, a second electrode layer 520, a firstinsulation layer 530, a first electrode layer 540, and a conductivesubstrate 550, which are stacked in sequence. The second electrode layer520 includes a partially exposed region in the interface of thesecond-conductivity type semiconductor layer 513. The first electrodelayer 540 includes at least one contact hole 541 which is electricallyconnected to the first-conductivity type semiconductor layer 511 andelectrically insulated from the second-conductivity type semiconductorlayer 513 and the active layer 512 so that the contact hole 541 extendsfrom one surface of the first electrode layer 540 to at least a portionof the first-conductivity type semiconductor layer 511.

Since the light emission of the semiconductor light emitting device 500is performed at the first-conductivity type semiconductor layer 511, theactive layer 512 and the second-conductivity type semiconductor layer513, they will be referred to as a light emitting stack structure 510.That is, the semiconductor light emitting device 500 includes the lightemitting stack structure 510, the first electrode layer 540 electricallyconnected to the first-conductivity type semiconductor layer 511, thesecond electrode layer 520 electrically connected to thesecond-conductivity type semiconductor layer 513, and the firstinsulation layer 530 electrically insulating the electrode layers 520and 540. Also, the conductive substrate 550 is included as a substratefor growth or support of the semiconductor light emitting device 500.

The semiconductor layers 511 and 513 may be formed of a semiconductormaterial, e.g., a GaN-based semiconductor, a SiC-based semiconductor, aZnO-based semiconductor, a GaAs-based semiconductor, a GaP-basedsemiconductor, a GaAsP-based semiconductor, etc. The semiconductorlayers 511 and 513 may be formed using a metal organic chemical vapordeposition (MOCVD) method, or a molecular beam epitaxy (MBE) method.Furthermore, the semiconductor layers 511 and 513 may be formed of amaterial selected from the group consisting of group III-Vsemiconductor, group IV-IV semiconductor, group II-VI semiconductor,group IV semiconductor such as Si, and combinations thereof. Thesemiconductor layers 511 and 513 are doped with proper impurities,considering the conductivity types thereof.

The active layer 512 is a layer which activates light emission, and isformed of a material having a smaller energy band gap than those of thefirst-conductivity type semiconductor layer 511 and thesecond-conductivity type semiconductor layer 513. For example, when thefirst-conductivity type semiconductor layer 511 and thesecond-conductivity type semiconductor layer 513 are formed of aGaN-based compound semiconductor, the active layer 512 may be formed ofan InAlGaN-based compound semiconductor having a smaller energy band gapthan that of GaN. That is, the active layer 512 may includeIn_(x)Al_(y)Ga_((1-x-y))N (where 0≦x≦1, 0≦y≦1, 0≦x+y≦1).

The wavelength of the emitted light may be adjusted by controlling amole ratio of the constituent materials of the active layer 512.Therefore, the semiconductor light emitting device 500 may emit infraredlight, visible light, or ultraviolet light according to characteristicsof the active layer 512.

Since the electrode layers 520 and 540 are layers which apply a voltageto the semiconductor layers having the same conductivity type, they mayinclude a metal, considering electrical conductivity. That is, theelectrodes 520 and 540 are electrodes which electrically connect thesemiconductor layers 511 and 513 to an external power source (notshown). For example, the electrode layers 520 and 540 as n-typeelectrodes may be formed of Ti, Al, Cr, or Au, and the electrode layers520 and 540 as p-type electrodes may be formed of Ni, Pd, Ag, Al, Pt, orAu.

The first electrode layer 540 is electrically connected to thefirst-conductivity type semiconductor layer 511, and the secondelectrode layer 520 is electrically connected to the second-conductivitytype semiconductor layer 513. Since the first electrode layer 540 andthe second electrode layer 520 are connected to different conductivitytype, they are electrically separated from each other by the firstinsulation layer 530. The first insulation layer 530 may be formed of amaterial having a low electrical conductivity. For example, the firstinsulation layer 530 may include an oxide, e.g., SiO₂.

The second electrode layer 520 reflects light generated from the activelayer 512. Since the second electrode layer 520 is disposed under theactive layer 512, it is disposed on a plane opposite to the direction inwhich light from the semiconductor light emitting device 500 travelswith respect to the active layer 520. Therefore, light traveling fromthe active layer 512 to the second electrode layer 520 is opposite tothe light emitting direction of the semiconductor light emitting device500. Thus, in order to increase luminous efficiency, light directed tothe second electrode layer 520 must be reflected. Therefore, if thesecond electrode layer 520 has a light reflection characteristic, thereflected light is directed to the light emitting plane, therebyincreasing the luminous efficiency of the semiconductor light emittingdevice 500.

In order to reflect the light emitted from the active layer 512, thesecond electrode layer 520 may be formed of a metal which is whitish inthe visible light range. For example, the second electrode layer 520 maybe formed of any one of Ag, Al, and Pt.

The second electrode layer 520 includes a partially exposed region inthe interface with the second-conductivity type semiconductor layer 513.The first electrode layer 540 contacts the conductive substrate 550 onthe bottom surface thereof, and is electrically connected to theexternal power source (not shown) through the conductive substrate 550.However, the second electrode layer 520 requires a separate connectionregion for connection with the external power source (not shown).Therefore, the second electrode layer 520 has a region exposed byetching a portion of the light emitting stack structure 510.

FIG. 19 illustrates an embodiment of a via hole 514 formed by etchingthe center portion of the light emitting stack structure 510 for theexposed region of the second electrode layer 520. An electrode pad part560 may be further formed on the exposed region of the second electrodelayer 520. The second electrode layer 520 may be electrically connectedto the external power source (not shown) through the exposed region. Atthis time, the second electrode layer 520 may be electrically connectedto the external power source (not shown) by the electrode pad part 560.The connection to the external power source (not shown) may be achievedusing wires. Thus, for convenience, the diameter of the via hole 514increases in a direction from the second electrode layer to thefirst-conductivity type semiconductor layer.

The via hole 514 is formed by a selective etching process which etchesthe light emitting stack structure 510, but does not etch the secondelectrode layer 520 including a metal. The diameter of the via hole 514may be appropriately determined by those skilled in the art, consideringthe light emitting area, the electrical connection efficiency, and thecurrent dispersion in the second electrode layer 520.

The first electrode layer 540 includes at least one contact hole 541which is electrically connected to the first-conductivity typesemiconductor layer 511 and electrically insulated from thesecond-conductivity type semiconductor layer 513 and the active layer512 so that the contact hole 541 extends to at least a portion of thefirst-conductivity type semiconductor layer 511. In order to create aconnection between the first-conductivity type semiconductor layer 511and the external power source (not shown), the first electrode layer 540includes at least one contact hole 541 passing through the secondelectrode layer 520 between the first electrode layer 540 and thesecond-conductivity type semiconductor layer 513, thesecond-conductivity type semiconductor layer 513, and the active layer512, extending to the first-conductivity type semiconductor layer 511,and including an electrode material.

If the contact hole 541 is provided for the electrical connection only,the first electrode layer 540 may include only one contact hole 541. Onthe other hand, if the contact hole 541 is also provided for the uniformdispersion of the current transferred to the first-conductivity typesemiconductor layer 511, the first electrode layer 540 may include aplurality of contact holes 541 at predetermined positions.

The conductive substrate 550 contacts the second electrode layer 520 andis electrically connected thereto. The conductive substrate 550 may be ametal substrate or a semiconductor substrate. When the conductivesubstrate 550 is a metal substrate, it may be formed of any one of Au,Ni, Cu, Al, and W. When the conductive substrate 550 is a semiconductorsubstrate, it may be formed of any one of Si, Ge, and GaAs. Also, theconductive substrate 550 may be formed of a material including Au, Ni,Al, Cu, W, Si, Se, and GaAs, for example, SiAl, which is a combinationof Si and Al. The conductive substrate 550 may be a growth substrate, ora support substrate. In the case of the support substrate, after using anonconductive substrate (e.g., a sapphire substrate) as a growthsubstrate, the nonconductive substrate is removed and the resultingstructure is attached.

When the conductive substrate 550 is the support substrate, it may beformed using a plating method or a substrate bonding method.Specifically, the conductive substrate 550 is formed in thesemiconductor light emitting device 500 by a plating method, which formsa substrate by forming a plating seed layer, or a substrate bondingmethod, which separately prepares the conductive substrate 550 andattaches it using a conductive adhesive, e.g., Au, Sn, Ni, Au—Sn, Ni—Sn,Ni—Au—Sn, Pb—Sr, etc.

FIG. 20 is a plan view of the semiconductor light emitting device 500. Avia hole 514 is formed on the top surface of the semiconductor lightemitting device 500, and an electrode pad part 560 is disposed in anexposed region formed in the second electrode layer 520. Although notshown on the top surface of the semiconductor light emitting device 500,the contact hole 541 is indicated by dotted lines in order to mark theposition of the contact hole 541. A first insulation layer 530 mayextend around the contact hole 541 in order to electrically separate thecontact hole 541 from the second electrode layer 520, thesecond-conductivity type semiconductor layer 513, and the active layer512. A further description will be made below with reference to FIGS.21B and 21C.

FIGS. 21A through 21C are cross-sectional views of the semiconductorlight emitting device illustrated in FIG. 20, taken along lines A-A′,B-B′ and C-C′, respectively. The line A-A′ is selected to take thesection of the semiconductor light emitting device 500, and the lineB-B′ is selected to take the section which includes the contact hole 541and the via hole 514. The line C-C′ is selected to take the sectionwhich includes the contact hole 541 only. The following description willbe made with reference to FIGS. 19 through 21C.

Referring to FIG. 21A, the contact hole 541 or the via hole 514 is notshown. The contact hole 541 is not connected through a separateconnection line, but electrically connected through the first electrodelayer 540. Thus, the contact hole 541 is not shown in the A-A′ section.

Referring to FIGS. 21B and 21C, the contact hole 541 extends from theinterface between the first electrode layer 540 and the second electrodelayer 520 to the inside of the first-conductivity type semiconductorlayer 511. The contact hole 541 passes through the second-conductivitytype semiconductor layer 513 and the active layer 512 and extends up tothe first-conductivity type semiconductor layer 511. The contact hole541 extends up to the interface between at least the active layer 512and the first-conductivity type semiconductor layer 511. Since thecontact hole 530 is provided for the purpose of electrical connectionand current dispersion, the purpose is achieved only if the contact hole541 contacts the first-conductivity type semiconductor layer 511. Hence,the contact hole 541 need not extend up to the outer surface of thefirst-conductivity type semiconductor layer 511.

The contact hole 541 must have a predetermined area because it is formedfor dispersing the current to the first-conductivity type semiconductorlayer 511. A predetermined number of contact holes 541 may be formed insuch a small area that the current may be uniformly dispersed on thefirst-conductivity type semiconductor layer 511. If a very small numberof contact holes 541 are formed, the current dispersion is difficult andthe electrical characteristics are degraded. If a very large number ofthe contact holes 541 are formed, the fabrication process is difficultand the active layer is reduced, causing the reduction in the lightemitting area. Thus, the number of contact holes 541 may beappropriately selected, taking into consideration those conditions.Therefore, the contact holes 541 are implemented in a shape whichoccupies an area as small as possible and is effective in currentdispersion.

The contact hole 541 extends from the second electrode layer 520 to theinside of the first-conductivity type semiconductor layer 511. Since thecontact hole 541 is formed for the current dispersion of thefirst-conductivity type semiconductor layer 511, the contact hole 541needs to be electrically separated from the second-conductivity typesemiconductor layer 513 and the active layer 512. Hence, the contacthole 541 is electrically separated from the second electrode layer 520,the second-conductivity type semiconductor layer 513, and the activelayer 512. Thus, the first insulation layer 530 may extend whilesurrounding the contact hole 541. The electrical separation may beperformed using an insulating material such as a dielectric.

Referring to FIG. 21B, the exposed region of the second electrode layer520 is a region for the electrical connection to the external powersource (not shown). The electrode pad part 560 may be disposed in theexposed region. At this time, a second insulation layer 570 may beformed at the inner surface of the via hole 541, so that the lightemitting stack structure 510 and the electrode pad part 560 areelectrically separated from each other.

Referring to FIG. 21A, since the first electrode layer 540 and thesecond electrode layer 520 are disposed on the same plane, thesemiconductor light emitting device 500 may exhibit a characteristic ofa horizontal type semiconductor light emitting device. In FIG. 21C,since the electrode pad part 560 is disposed on the surface of thefirst-conductivity type semiconductor layer 511, the semiconductor lightemitting device 500 may exhibit a characteristic of a vertical typesemiconductor light emitting device. Therefore, the semiconductor lightemitting device 500 has a hybrid type structure having both thehorizontal type and the vertical type.

In FIGS. 21A through 21C, the first-conductivity type semiconductorlayer 511 may be an n-type semiconductor layer, and the first electrodelayer 540 may be an n-type electrode. In this case, thesecond-conductivity type semiconductor layer 513 may be a p-typesemiconductor layer, and the second electrode layer 520 may be a p-typeelectrode. Thus, the first electrode layer 540 being the n-typeelectrode and the second electrode layer 520 being the p-type electrodemay be electrically insulated from each other, with the first insulationlayer 530 disposed therebetween.

FIG. 22 illustrates the light emission of a semiconductor light emittingdevice having an uneven pattern on the surface thereof according to anembodiment of the present invention. The description of the elementshaving already been described above will be omitted.

In the semiconductor light emitting device 500 according to thisembodiment of the present invention, the outermost surface in the lighttraveling direction is provided with the first-conductivity typesemiconductor layer 511. Therefore, the uneven pattern 580 on thesurface of the semiconductor light emitting device may be formed using amethod known in the art such as lithography. In this case, the lightemitted from the active layer 512 is extracted while passing through theuneven pattern 580 formed on the surface of the first-conductivity typesemiconductor layer 511. Thus, the light extraction efficiency isincreased by the uneven pattern 580.

The uneven pattern 580 may have a photonic crystal structure. A photoniccrystal structure is a structure in which media having differentrefractive indexes are arranged regularly in a crystal-like manner. Thephotonic crystal structure may further increase light extractionefficiency because it can adjust light on the basis of length unitcorresponding to the multiple of the wavelength of light.

FIG. 23 illustrates the exposure of the second electrode layer at anedge in the semiconductor light emitting device according to thisembodiment of the present invention.

According to one aspect of the present invention, there is provided amethod for manufacturing a semiconductor light emitting device,including: sequentially forming a first-conductivity type semiconductorlayer 511′, an active layer 512′, a second-conductivity typesemiconductor layer 513′, a second electrode layer 520′, an insulationlayer 530′, a first electrode layer 540′, and a conductive substrate550′; forming a partially exposed region in the interface between thesecond electrode layer 520′ and the second-conductivity typesemiconductor layer 513′; and forming at least one contact hole 541′extending from one surface of the first electrode layer 540 to at leasta portion of the first-conductivity type semiconductor layer 511′, thefirst electrode layer 540′ being electrically connected to thefirst-conductivity type semiconductor layer 511′ and electricallyinsulated from the second-conductivity type semiconductor layer 513′ andthe active layer 512′.

In this case, the exposed region of the second electrode layer 520′ maybe provided by forming the via hole 514′ in the light emitting stackstructure 510′ (see FIG. 19), or may be formed by mesa etching the lightemitting stack structure 510′ (see FIG. 23). A description of elementsthe same as those of the embodiment described above with reference toFIG. 19 will be omitted.

Referring to FIG. 23, an edge of the semiconductor light emitting device500′ is mesa etched. The etching is performed on the light emittingstack structure 510′ so that the second electrode layer 520′ is exposedin the interface with the second-conductivity type semiconductor layer513′. Therefore, the exposed region of the second electrode layer 520′is formed at the edge of the semiconductor light emitting device 500′.When compared with the above-described embodiment which forms the viahole, the case of forming the exposed region of the second electrodelayer 520′ at the edge may be performed by a simple process and thesubsequent electrical connection process may also be performed easily.

A semiconductor light emitting device according to another embodiment ofthe present invention will be described below with reference to FIGS. 24through 34.

FIG. 24 is a schematic perspective view of a semiconductor lightemitting device according to another embodiment of the presentinvention, and FIG. 25 is a top plan view of the semiconductor lightemitting device illustrated in FIG. 24. FIG. 26 is a cross-sectionalview of the semiconductor light emitting device illustrated in FIG. 25,taken along line A-A′. The semiconductor light emitting device will bedescribed below with reference to FIGS. 24 and 26.

The semiconductor light emitting device 600 according to this embodimentof the present invention includes a first-conductivity typesemiconductor layer 611, an active layer 612, a second-conductivity typesemiconductor layer 613, a second electrode layer 620, an insulationlayer 630, a first electrode layer 640, and a conductive substrate 650,which are stacked in sequence. In order for an electrical connection tobe made with the first-conductive semiconductor layer 611, the firstelectrode layer 640 includes at least one contact hole 641 which iselectrically insulated from the second-conductivity type semiconductorlayer 613 and the active layer 612 so that the contact hole 641 extendsfrom one surface of the first electrode layer 640 to at least a portionof the first-conductivity type semiconductor layer 611. In thisembodiment, the first electrode layer 640 is not a requisite element.Although not shown, the semiconductor light emitting device 600 may notinclude the first electrode layer 640, and the contact hole 641 may beformed from one surface of the conductive substrate 650. That is, inorder for electrical connection to the first-conductivity typesemiconductor layer 611, the conductive substrate 650 may include atleast one contact hole 641 which is electrically insulated from thesecond-conductivity type semiconductor layer 613 and the active layer612 and extends from one surface of the first electrode layer 640 to atleast a portion of the first-conductivity type semiconductor layer 611.In this case, the conductive substrate 650 is electrically connected tothe external power source (not shown), and a voltage is applied to thefirst-conductivity type semiconductor layer 611 through the conductivesubstrate 650.

The second electrode layer 620 includes a partially exposed region 614in the interface with the second-conductivity type semiconductor layer613. The exposed region 614 may be formed by etching thefirst-conductivity type semiconductor layer 611, the active layer 612,and the second-conductivity type semiconductor layer 613. An etch stoplayer 621 is formed in the exposed region 614.

Since the light emission of the semiconductor light emitting device 600is performed at the first-conductivity type semiconductor layer 611, theactive layer 612 and the second-conductivity type semiconductor layer613, they will be referred to as a light emitting stack structure 610.That is, the semiconductor light emitting device 600 includes the lightemitting stack structure 610, the first electrode layer 640 electricallyconnected to the first-conductivity type semiconductor layer 611 throughthe contact hole 641, the second electrode layer 620 electricallyconnected to the second-conductivity type semiconductor layer 613, andthe insulation layer 630 electrically insulating the electrode layers620 and 640. Also, the conductive substrate 650 is included in order forsupporting the semiconductor light emitting device 600.

The semiconductor layers 511 and 513 may be formed of, but are notlimited to, a semiconductor material, e.g., a GaN-based semiconductor, aSiC-based semiconductor, a ZnO-based semiconductor, a GaAs-basedsemiconductor, a GaP-based semiconductor, a GaAsP-based semiconductor,etc. Furthermore, the semiconductor layers 611 and 613 may be formed ofa material selected from the group consisting of a group III-Vsemiconductor, a group IV-IV semiconductor, a group II-VI semiconductor,a group IV semiconductor such as Si, and combinations thereof. Moreover,the semiconductor layers 611 and 613 are doped with n-type impurity orp-type impurity, considering the conductivity types thereof.

The active layer 612 is a layer which activates light emission, and isformed of a material having a small energy band gap than those of thefirst-conductivity type semiconductor layer 611 and thesecond-conductivity type semiconductor layer 613. For example, when thefirst-conductivity type semiconductor layer 611 and thesecond-conductivity type semiconductor layer 613 are formed of aGaN-based compound semiconductor, the active layer 612 may be formed ofan InAlGaN-based compound semiconductor having a smaller energy band gapthan that of GaN. That is, the active layer 612 may includeIn_(x)Al_(y)Ga_((1-x-y))N (where 0≦x≦1, 0≦y≦1, 0≦x+y≦1).

In this case, in view of the characteristics of the active layer 612,impurities are not doped. The wavelength of the emitted light may beadjusted by controlling a mole ratio of the constituent materials of theactive layer 612. Therefore, the semiconductor light emitting device 600may emit infrared light, visible light, or ultraviolet light accordingto characteristics of the active layer 612.

Since the first electrode layer 640 and the second electrode layer 620are layers which apply a voltage to the semiconductor layers having thesame conductivity type, the semiconductor layers 611 and 613 areelectrically connected to the external power source (not shown) by theelectrode layers 620 and 640.

The first electrode layer 640 is electrically connected to thefirst-conductivity type semiconductor layer 611, and the secondelectrode layer 620 is electrically connected to the second-conductivitytype semiconductor layer 613. Thus, the first electrode layer 640 andthe second electrode layer 620 are electrically separated from eachother by the insulation layer 630. The insulation layer 630 may beformed of a material having a low electrical conductivity. For example,the insulation layer 630 may include oxide, e.g., SiO₂.

In order for an electrical connection to be made with to thefirst-conductivity type semiconductor layer 611, the first electrodelayer 640 includes at least one contact hole 641 which is electricallyinsulated from the second-conductivity type semiconductor layer 613 andthe active layer 612 (the insulation layer 630 disposed between thefirst electrode layer and the second electrode layer may extend) andextends up to a portion of the first-conductivity type semiconductorlayer 611. The contact hole 641 passes through the second electrodelayer 620, the insulation layer 630, and the active layer 612 andextends to the first-conductivity type semiconductor layer 611. Thecontact hole 641 includes an electrode material. Due to the contact hole641, the first electrode layer 640 and the first-conductivity typesemiconductor layer 611 are electrically connected together, so that thefirst-conductivity type semiconductor layer 611 is connected to theexternal power source (not shown).

If the contact hole 641 is provided only for the electrical connectionof the first-conductivity type semiconductor layer 611, the firstelectrode layer 640 may include only one contact hole 641. On the otherhand, if the contact hole 641 is also provided for the uniformdispersion of the current transferred to the first-conductivity typesemiconductor layer 611, the first electrode layer 640 may include aplurality of contact holes 641 at predetermined positions.

Since the second electrode layer 620 is disposed under the active layer612, it is disposed on a plane opposite to the light emitting directionof the semiconductor light emitting device 600 with respect to theactive layer 612. Therefore, in order to increase the luminousefficiency, light directed to the second electrode layer 620 must bereflected.

In order to reflect the light emitted from the active layer 612, thesecond electrode layer 620 may be formed of a metal which is whitish inthe visible light range. For example, the second electrode layer 620 maybe formed of any one of Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, and Au.

A portion of the second electrode layer 620 is exposed in the interfacewith the second-conductivity type semiconductor layer 613 by the etchingof the first-conductivity type semiconductor layer 611, the active layer612, and the second-conductivity type semiconductor layer 613. The etchstop layer 621 is formed in the exposed region 614. The first electrodelayer 640 contacts the conductive substrate 650 on the bottom surfacethereof, so that it is electrically connected to the external powersource (not shown). On the other hand, the second electrode layer 620requires a separate connection region for connection with the externalpower source (not shown). Therefore, the second electrode layer 620 hasthe exposed region 614 at a portion of the interface with thesecond-conductivity type semiconductor layer 613. The exposed region 614is formed by etching a portion of the light emitting stack structure610. In this way, the second-conductivity type semiconductor layer 613is electrically connected to the external power source (not shown) bythe second electrode layer 620.

The area of the exposed region 614 may be appropriately determined bythose skilled in the art, considering the light emitting area, theelectrical connection efficiency, and the current dispersion in thesecond electrode layer 620. An embodiment where the edge of the lightemitting stack structure 610 is etched so that the exposed region 614 ofthe second electrode layer 620 is disposed at the edge is illustrated inFIGS. 24 through 26.

The exposed region 614 is formed by a selective etching process whichetches a portion of the light emitting stack structure 610, but does notetch the second electrode layer 620 including a metal. However, since itis difficult to exactly control the selective etching process of etchinga portion of the light emitting stack structure 610, the secondelectrode layer 620 disposed under the light emitting stack structure610 may be partially etched. When a portion of the second electrodelayer 620 is etched, the metal material of the second electrode layer620 is attached to the second-conductivity type semiconductor layer 613,causing a leakage current. Therefore, the etch stop layer 621 is formedin the region of the light emitting stack structure 610 to which theetching process is performed, that is, the exposed region of the secondelectrode layer 620.

The etch stop layer 621 prevents the metal of the second electrode layer620 from being attached to the side surface of the light emitting stackstructure 610. Consequently, leakage current may be reduced and theetching process may be easily performed. The etch stop layer 621 may beformed of a material suppressing the etching of the light emitting stackstructure 610. For example, the etch stop layer 621 may be formed of,but is not limited to, an insulating material, e.g., silicon oxide orsilicon nitride, such as SiO₂, SiO_(x)N_(y), Si_(x)N_(y), etc. The etchstop layer 621 is not necessarily formed of an insulating material. Eventhough the etch stop layer 621 is formed of a conductive material, itdoes not affect the operation of the semiconductor light emitting device600. Therefore, the etch stop layer 621 may be formed of an appropriateconductive material only if the conductive material can perform the etchstop function.

Alternatively, an electrode pad part 660 passing through the etch stoplayer 621 may be formed in the exposed region 614. The electrode padpart 660 passes through the etch stop layer 621 and is electricallyconnected to the second electrode layer 620. In this case, it is easy toelectrically connect the second electrode layer 620 to the externalpower source (not shown).

The conductive substrate 650 is disposed on the bottom surface of thefirst electrode layer 640. The conductive substrate 650 contacts thefirst electrode layer 640 and is electrically connected thereto. Theconductive substrate 650 may be a metal substrate or a semiconductorsubstrate. The conductive substrate 650 may be formed of any one of Au,Ni, Cu, Al, W, Si, Se, and GaAs, for example, pure Cu or SiAl, acombination of Si and Al. In this case, the conductive substrate 650 maybe formed using a plating method or a bonding method. The conductivesubstrate 650 may be a support substrate. In the case of the supportsubstrate, after using a sapphire substrate as a growth substrate, thesapphire substrate is removed and the resulting structure is attached.

FIG. 25 is a top plan view of the semiconductor light emitting device600. Although not shown in the top surface of the semiconductor lightemitting device 600, the contact hole 641 is indicated by dotted linesin order to mark the position of the contact hole 641. The insulationlayer 630 may extend around the contact hole 641 in order toelectrically separate the contact hole 641 from the second electrodelayer 620, the second-conductivity type semiconductor layer 613, and theactive layer 612. A further description will be made below withreference to FIG. 26.

FIG. 26 is a cross-sectional view of the semiconductor light emittingdevice 600 illustrated in FIG. 25, taken along line A-A′. The line A-A′is selected to take the section which includes the contact hole 641 andthe exposed region 614.

Referring to FIG. 26, the contact hole 641 extends from the interface ofthe first electrode layer 640 to the inside of the first-conductivitytype semiconductor layer 611 while passing through the second electrodelayer 620, the second-conductivity type semiconductor layer 613, and theactive layer 612. The contact hole 641 extends up to the interfacebetween at least the active layer 612 and the first-conductivity typesemiconductor layer 611, preferably, a portion of the first-conductivitytype semiconductor layer 611. Since the contact hole 641 is provided forthe purpose of the electrical connection and current dispersion of thefirst-conductivity type semiconductor layer 611, the purpose is achievedonly if the contact hole 641 contacts the first-conductivity typesemiconductor layer 611. Hence, the contact hole 641 need not extend upto the outer surface of the first-conductivity type semiconductor layer611.

Furthermore, the contact hole 641 must have a predetermined area becauseit is formed for dispersing the current to the first-conductivity typesemiconductor layer 611. A predetermined number of the contact holes 641may be formed in such a small area that current may be uniformlydispersed on the first-conductivity type semiconductor layer 611. If avery small number of the contact holes 641 are formed, the currentdispersion is difficult and the electrical characteristics are degraded.If a very large number of the contact holes 641 are formed, thefabrication process is difficult and the active layer is reduced,causing the reduction in the light emitting area. Thus, the number ofthe contact holes 641 may be appropriately selected, taking intoconsideration those conditions. Therefore, the contact holes 641 areimplemented in a shape which occupies an area as small as possible andis effective in the current dispersion.

The contact hole 641 extends from the first electrode layer 640 to theinside of the first-conductivity type semiconductor layer 611. Since thecontact hole 641 is formed for the current dispersion of thefirst-conductivity type semiconductor layer 611, the contact hole 641needs to be electrically separated from the second-conductivity typesemiconductor layer 613 and the active layer 612. Hence, the insulationlayer 630 may extend while surrounding the contact hole 641.

Referring to FIG. 26, the second electrode layer 620 includes apartially exposed region 614 in the interface with thesecond-conductivity type semiconductor layer 613. The exposed region 614is a region for an electrical connection between the second electrodelayer 620 and the external power source (not shown). The etch stop layer621 is formed in the exposed region 614. The semiconductor lightemitting device 600 may further include the electrode pad part 660 whichpasses through the etch stop layer 621 and is electrically connected tothe second electrode layer 620. At this time, an insulation layer 670may be formed in the inner surface of the exposed region 614 in orderfor electrically separating the light emitting stack structure 610 fromthe electrode pad part 660.

In FIG. 26, since the first electrode layer 640 and the second electrodelayer 620 are disposed on the same plane, the semiconductor lightemitting device 600 may exhibit a characteristic of a horizontal typesemiconductor light emitting device. Since the electrode pad part 660 isdisposed on the surface of the first-conductivity type semiconductorlayer 611, the semiconductor light emitting device 600 may exhibit acharacteristic of a vertical type semiconductor light emitting device.Therefore, the semiconductor light emitting device 600 has a hybrid typestructure having both the horizontal type and the vertical type.

FIGS. 27 through 29 illustrate a semiconductor light emitting deviceaccording to another embodiment of the present invention. Specifically,FIG. 27 is a perspective view of the semiconductor light emitting deviceand FIG. 28 is a top plan view of the semiconductor light emittingdevice. FIG. 29 is a cross-sectional view of the semiconductor lightemitting device illustrated in FIG. 28, taken along line A-A′.

Referring to FIGS. 27 through 29, a center portion of a light emittingstack structure 710 is etched. Thus, a partially exposed region 714 inthe interface between a second electrode layer 720 and asecond-conductivity type semiconductor layer is disposed at the centerportion of the semiconductor light emitting device 700. The descriptionof the same elements having already been described above will beomitted. The semiconductor light emitting device 700 may include anelectrode pad part 760 which is formed by removing a portion of an etchstop layer 721 formed in the exposed region. The electrode pad part 760may be electrically connected to an external power source (not shown),and may pass through the etch stop layer 721 and be electricallyconnected to the second electrode layer 720. The connection to theexternal power source (not shown) may be achieved using wires. Thus, forconvenience of connection, the exposed region 714 may be formed so thatit increases in a direction from the second electrode layer 720 to thefirst-conductivity type semiconductor layer.

FIGS. 30 and 31 illustrate a semiconductor light emitting deviceaccording to a modified embodiment of the present invention.Specifically, FIGS. 39 and 31 are a perspective view and across-sectional view of the semiconductor light emitting device,respectively. In this case, the top plan view of the semiconductor lightemitting device is similar to that of FIG. 25, and FIG. 31 is across-sectional view taken along line A-A′, which is similar to that ofFIG. 26. The description of the same elements having already beendescribed above will be omitted.

Referring to FIGS. 30 and 31, a second electrode layer is exposed by theetching of a light emitting stack structure 610′, and an etch stop layer621′ formed in the exposed region extends to the sides of asecond-conductivity type semiconductor layer 613′ and an active layer612′. In this case, it is possible to prevent a metal material of thesecond electrode layer from being attached to the semiconductor sideduring the etching of the first-conductivity type semiconductor layer611′ as described above. Furthermore, the active layer 612′ isprotected.

Such a semiconductor light emitting structure will be described below.

FIGS. 32A through 32D are cross-sectional views illustrating a methodfor manufacturing a semiconductor light emitting device according to anembodiment of the present invention, more specifically, thesemiconductor light emitting device of FIGS. 24 through 26.

Referring to FIG. 32A, a first-conductivity type semiconductor layer611, an active layer 612, a second-conductivity type semiconductor layer613, and a second electrode layer 620 are sequentially formed on anonconductive substrate 680.

In this case, the semiconductor layers 611 and 613 and the active layer612 may be formed using a known process, e.g., a metal organic chemicalvapor deposition (MOCVD) process, a molecular beam epitaxy (MBE)process, a hybrid vapor phase epitaxy (HVPE) process, etc. A sapphiresubstrate may be used as the nonconductive substrate 680 because it iseasy to grow a nitride semiconductor layer thereupon.

The second electrode layer 620 is stacked while forming an etch stoplayer 621 in a region to be exposed by the etching of thefirst-conductivity type semiconductor layer 611, the active layer 612,and the second-conductivity type semiconductor layer 613.

Next, an insulation layer 630 and a conductive substrate 650 are formedon the second electrode layer 620. As illustrated in FIG. 32B, a firstelectrode layer 640 may be formed between the insulation layer 630 andthe conductive substrate 650.

In order for an electrical connection to be made with thefirst-conductivity type semiconductor layer 611, the conductivesubstrate 650 is formed so that it includes at least one contact hole641 which is electrically insulated from the second-conductivity typesemiconductor layer 613 and the active layer 612 and extends from onesurface of the conductive substrate 650 to a portion of thefirst-conductivity type semiconductor layer 611.

As illustrated in FIG. 32A, when the first electrode layer 640 is formedbetween the insulation layer 630 and the conductive substrate 650, thecontact hole 641 is formed from one surface of the first electrode layer640. That is, in order for the electrical connection to thefirst-conductivity type semiconductor layer 611 to be made, the firstelectrode layer 640 is formed so that it includes at least one contacthole 641 which is electrically insulated from the second-conductivitytype semiconductor layer 613 and the active layer 612 and extends fromone surface of the first electrode layer 640 to a portion of thefirst-conductivity type semiconductor layer 611.

Since the contact hole 641 is provided for the current dispersion of thefirst-conductivity type semiconductor layer 611, the contact hole 641needs to be electrically separated from the second-conductivity typesemiconductor layer 613 and the active layer 612. Therefore, theinsulation layer 630 may extend while surrounding the contact hole 641.

Next, referring to FIG. 32C (which is illustrated by inverting FIG.32B), the nonconductive substrate 680 is removed, and thefirst-conductivity type semiconductor layer 611, the active layer 612,and a portion of the second-conductivity type semiconductor layer 613are etched to form an exposed region 614 at a portion of the interfacebetween the second electrode layer 620 and the second-conductivity typesemiconductor layer 613.

The exposed region 614 is formed by a selective etching process whichetches a portion of the light emitting stack structure 610 but does notetch the second electrode layer 620 including a metal.

As described above, since it is difficult to exactly control theselective etching process of etching a portion of the light emittingstack structure 610, the second electrode layer 620 disposed under thelight emitting stack structure 610 may be partially etched. However, inaccordance with this embodiment of the present invention, the etchingprocess may be easily performed by forming the etch stop layer 621 inthe region to which the etching process is performed. Consequently, itis possible to prevent the metal of the second electrode layer 620 frombeing attached to the side of the light emitting stack structure 610,thereby reducing a leakage current.

Next, referring to FIG. 32D, a portion of the etch stop layer 621 may beremoved in order for electrical connection between the second electrodelayer 620 and an external power source (not shown). In this case, anelectrode pad part 660 may be formed in the region where the etch stoplayer 621 is removed. Furthermore, in order to electrically separate thelight emitting stack structure 610 from the electrode pad part 660, aninsulation layer 670 may be formed at the inner surface of the lightemitting stack structure to which the etching process is performed.

FIGS. 32A through 32D illustrate an example in which an edge of thelight emitting stack structure 610 is etched and the exposed region ofthe second electrode layer 620 is formed at the edge. When the centerportion of the light emitting stack structure 610 is etched, thesemiconductor light emitting device illustrated in FIG. 27 may bemanufactured.

FIGS. 33A through 33D are cross-sectional views illustrating a methodfor manufacturing a semiconductor light emitting device according to amodified embodiment of the present invention, more specifically, amethod for manufacturing the semiconductor light emitting deviceillustrated in FIGS. 30 and 31. A description of elements the same asthose of FIGS. 32A through 32D will be omitted.

Referring to FIG. 33A, a first-conductivity type semiconductor layer611′, an active layer 612′, a second-conductivity type semiconductorlayer 613′, and a second electrode layer 620′ are sequentially formed ona nonconductive substrate 680′.

The second electrode layer 620′ is stacked while forming an etch stoplayer 621 in a region to be exposed by the etching of thefirst-conductivity type semiconductor layer 611′, the active layer 612′,and the second-conductivity type semiconductor layer 613′. Asillustrated in FIG. 33A, before etching a light emitting stack structure610′ for forming an exposed region 614′, the second-conductivity typesemiconductor layer 621′, the active layer 612′, and a portion of thefirst-conductivity type semiconductor layer 613′ are primarily etched.An etch stop layer 621′ extends in the second-conductivity typesemiconductor layer 621′, the active layer 612′, and the portion of thefirst-conductivity type semiconductor layer 613′ which are exposed bythe primary etching process.

In this case, as illustrated in FIG. 33C, the first-conductivity typesemiconductor layer 611′ only may be etched during the etching of thelight emitting stack structure 610′ for forming the exposed region 614′in the second electrode layer 620′, thereby obtaining an additionaleffect that protects the active layer 612′.

Referring to FIG. 33B, an insulation layer 630′, a first electrode layer640′, and a conductive substrate 650′ are formed on the second electrodelayer 620′.

In order for an electrical connection to be made with thefirst-conductivity type semiconductor layer 611′, the first electrodelayer 640′ is formed so that it includes at least one contact hole 641′which is electrically insulated from the second-conductivity typesemiconductor layer 613′ and the active layer 612′ and extends from onesurface of the first electrode layer 640′ to a portion of thefirst-conductivity type semiconductor layer 611′. Since the contact hole641′ is provided for the current dispersion of the first-conductivitytype semiconductor layer 611′, the contact hole 641′ needs to beelectrically separated from the second-conductivity type semiconductorlayer 613′ and the active layer 612′. Therefore, an insulation layer630′ may extend while surrounding the contact hole 641′.

Next, referring to FIG. 33C (which is illustrated by inverting FIG.33B), an exposed region 614′ is formed on the second electrode layer620′ so that a portion of the interface with the second-conductivitytype semiconductor layer 613′ is exposed. The nonconductive substrate680′ is removed, and the first-conductivity type semiconductor layer611′ is etched. Since the active layer 612′ and the second-conductivitytype semiconductor layer 613′ are etched as illustrated in FIG. 33A, theexposed region 614′ may be formed by the etching of thefirst-conductivity type semiconductor layer 611′ only.

As described above, the etching process may be easily performed byforming the etch stop layer 621′ in the exposed region of the secondelectrode layer 620′ during the etching of the light emitting stackstructure 610′. Furthermore, the active layer 612′ may be protectedbecause the first-conductivity type semiconductor layer 611′ only isetched by the primary etching process in FIG. 33A.

Next, referring to FIG. 33D, a portion of the etch stop layer 621′formed on the exposed region 614′ may be removed in order for anelectrical connection between the second electrode layer 620′ and theexternal power source (not shown) to be made. In this case, in order foran electrical connection to the second electrode layer 620′ to be made,an electrode pad part 660′ may be formed in the region where the etchstop layer 621′ is removed. Unlike the process of FIG. 32, only thefirst-conductivity type semiconductor layer 611′ is exposed, and thus itis unnecessary to form an insulation layer in order for electricalseparation from the electrode pad part 660′.

When the semiconductor light emitting devices 600, 600′ and 700according to the embodiments of the present invention are packaged, theconductive substrates 650, 650 and 750 are electrically connected to afirst lead frame, and the electrode pad parts 660, 660′ and 760 areelectrically connected to a second lead frame through wires. That is,since the semiconductor light emitting devices 600, 600′ and 700 may bepackaged in a combined manner of die bonding and wire bonding, maximumluminous efficiency may be ensured and the manufacturing process may beperformed at a relatively low cost.

FIG. 34 is a schematic cross-sectional view of a semiconductor lightemitting device according to another modified embodiment of the presentinvention. Referring to FIG. 34, like the above-described embodiments,the semiconductor light emitting device 600″ according to the modifiedembodiment of the present invention includes a first-conductivity typesemiconductor layer 611″, an active layer 612″, a second-conductivitytype semiconductor layer 613″, a second electrode layer 620″, aninsulation layer 630″, a first electrode layer 640″, a conductivitysubstrate 650″, an etch stop layer 621″, and an electrode pad part 660″,which are sequentially stacked. In order for an electrical connection tobe made with the first-conductivity type semiconductor layer 611″, thefirst electrode layer 640″ includes at least one contact hole 641″ whichis electrically insulated from the second-conductivity typesemiconductor layer 613″ and the active layer 612″ and extends from onesurface of the first electrode layer 640″ to at least a portion of thefirst-conductivity type semiconductor layer 612″. In this modifiedembodiment, a passivation layer 670″ having an uneven structure isfurther provided. The description of the same elements as thosedescribed above will be omitted, and the passivation layer 670″ onlywill be described below.

When the structure provided with the first-conductivity typesemiconductor layer 611″, the active layer 612″, and thesecond-conductivity type semiconductor layer 613″ is defined as a lightemitting structure, the passivation layer 670″ is formed to cover theside surface of the light emitting structure. Thus, the passivationlayer 670″ functions to protect the light emitting structure,specifically, the active layer 612″. In this case, as illustrated inFIG. 34, the passivation layer 670″ may be formed on the top surface ofthe light emitting structure, as well as the side surface of the lightemitting structure, or may also be formed on the top surface of the etchstop layer 620″.

In order to perform the function of protecting the light emittingstructure, the passivation layer 670″ may be formed of silicon oxide orsilicon nitride, e.g., SiO₂, SiO_(x)N_(y), Si_(x)N_(y), etc., and mayhave a thickness of approximately 0.1-2 μm. Accordingly, the passivationlayer 670″ may have a refractive index of approximately 1.4-2.0. Due toair or package mold structure and refractive index differences, it maybe problematic for light emitted from the active layer 670″ to bereleased. In this embodiment, external light extraction efficiency isimproved by forming the uneven structure in the passivation layer 670″.In particular, as illustrated in FIG. 34, when the uneven structure isformed in a region through which light emitted in a lateral directionrelative to the active layer 612″ passes, the amount of light emitted tothe side surface of the semiconductor light emitting device 600″ mayincreases. Specifically, in a comparison between the case in which theuneven structure is employed in the passivation layer 670″ and the casein which no uneven structure is employed therein, in a state where allelements other than the uneven structure are identical, the lightextraction efficiency was improved more than 5%. Meanwhile, although notnecessarily required, the uneven structure of the passivation layer 670″may be formed in a region corresponding to the top surface of thefirst-conductivity type semiconductor layer 611″. In this case, thelight extraction efficiency in a vertical direction may be improved.Furthermore, the uneven structure may be formed in the side surface ofthe passivation layer 670″.

A semiconductor light emitting device according to another embodiment ofthe present invention will be described below with reference to FIGS. 35through 55.

FIG. 35 is a schematic perspective view of a semiconductor lightemitting device according to another embodiment of the presentinvention. FIG. 36 is a top plan view of the semiconductor lightemitting device illustrated in FIG. 35. FIG. 37 is a cross-sectionalview taken along line A-A′ of FIG. 36. Referring to FIGS. 35 through 37,the semiconductor light emitting device 800 according to this embodimentof the present invention includes a first-conductivity type contactlayer 804 on a conductive substrate 807. A light emitting structure isformed on the first-conductivity type contact layer 804. The lightemitting structure includes a first-conductivity type semiconductorlayer 803, an active layer 802, and a second-conductivity typesemiconductor layer 801. A high resistance part 808 is formed at theside surface of the light emitting structure. As will be describedlater, the high resistance part 808 may be obtained by injecting ionsinto the side surface of the light emitting structure. Thefirst-conductivity type contact layer 804 is electrically separated fromthe conductive substrate 807. To this end, an insulator 806 is disposedbetween the first-conductivity type contact layer 804 and the conductivesubstrate 807.

In this embodiment, the first-conductivity type semiconductor layer 803and the second-conductivity type semiconductor layer 801 may be a p-typesemiconductor layer and an n-type semiconductor layer, respectively, andmay be formed of nitride semiconductors. In this embodiment, thefirst-conductivity type and the second-conductivity type may beunderstood as, but are not limited to, p-type and n-type, respectively.The first-conductivity type semiconductor layer 803 and thesecond-conductivity type semiconductor layer 801 have a composition ofAl_(x)In_(y)Ga_((1-x-y))N (where 0≦x≦1, 0≦y≦1, 0≦x+y≦1), e.g., GaN,AlGaN, InGaN, etc. The active layer 802 formed between thefirst-conductivity type semiconductor layer 803 and thesecond-conductivity type semiconductor layer 801 emits light having apredetermined energy due to the recombination of electrons and holes andmay have a multiple quantum well (MQW) structure in which a quantum welllayer and a quantum barrier layer are alternately stacked. For example,an InGaN/GaN structure may be used for the multiple quantum wellstructure.

The first-conductivity type contact layer 804 may reflect light emittedfrom the active layer 802 toward the top of the semiconductor lightemitting device 800, i.e., the second-conductivity type semiconductorlayer 801. Furthermore, the first-conductivity type contact layer 804may form an ohmic contact with the first-conductivity type semiconductorlayer 803. Considering this function, the first-conductivity typecontact layer 804 may include Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, orAu. In this case, although not illustrated in detail, thefirst-conductivity type contact layer 804 may have a structure capableof improving the reflection efficiency. Specifically, thefirst-conductivity type contact layer 804 may have a structure includingat least one of Al, Ag, Ni/Ag, Zn/Ag, Ni/Al, Zn/Al, Pd/Ag, Pd/Al, Ir/Ag,Ir/Au, Pt/Ag, Pt/Al, Ni/Ag/Pt, and combinations thereof. In thisembodiment, a portion of the first-conductivity type contact layer 804may be exposed to the outside. As illustrated, the exposed region may bea region where the light emitting structure is not formed. The exposedregion of the first-conductivity type contact layer 804 corresponds toan electrical connection part for applying an electric signal, and anelectrode pad 805 may be formed on the exposed region of thefirst-conductivity type contact layer 804.

As will be described later, the conductive substrate 807 functions as asupport body which supports the light emitting structure in a laserlift-off process or the like. The conductive substrate 807 may includeat least one material selected from the group consisting of Au, Ni, Al,Cu, W, Si, Se, and GaAs, for example, pure Cu or AlSi, a combination ofSi and Al. In this case, the conductive substrate 807 may be formedusing a plating method or a bonding method according to the selectedmaterial. In this embodiment, the conductive substrate 807 iselectrically connected to the second-conductivity type semiconductorlayer 801. Accordingly, the electric signal may be applied to thesecond-conductivity type semiconductor layer 801 through the conductivesubstrate 807. To this end, as illustrated in FIGS. 37 and 38, it isnecessary to provide a conductive via v which extends from theconductive substrate 807 and is electrically connected to thesecond-conductivity type semiconductor layer 801.

The conductive via v is connected to the inside of thesecond-conductivity type semiconductor layer 801. To reduce the contactresistance, the number, shape and pitch of the conductivity via v andits contact area with the second-conductivity type semiconductor layer801 may be appropriately adjusted. In this case, since the conductivevia v needs to be electrically separated from the active layer 802, thefirst-conductivity type semiconductor layer 803, and thefirst-conductivity type contact layer 804, an insulator 806 is formedbetween the conductive via v and the respective layers 802, 803 and 804.The insulator 806 may be formed of any material if it has an electricalinsulation characteristic. Preferably, the insulator 806 is formed of amaterial which absorbs low amounts of light. For example, the insulator806 may be formed of silicon oxide, silicon nitride, or anotherinsulating material, e.g., SiO₂, SiO_(x)N_(y), Si_(x)N_(y), etc.

As described above, in this embodiment, the conductive substrate 807 iselectrically connected to the second-conductivity type semiconductorlayer 801 through the conductive via v, and it is unnecessary toseparately form an electrode on the top surface of thesecond-conductivity type semiconductor layer 801. Accordingly, theamount of light emitted to the top surface of the second-conductivitytype semiconductor layer 801 may increase. In this case, since theconductive via v is formed at a portion of the active layer 802, thelight emitting region is reduced. However, since no electrode is formedon the top surface of the second-conductivity type semiconductor layer801, light extraction efficiency may be further improved. Meanwhile, inthe semiconductor light emitting device 800 according to this embodimentof the present invention, since no electrode is disposed on the topsurface of the second-conductivity type semiconductor layer 801, theentire electrode arrangement is similar to a horizontal electrodestructure rather than a vertical electrode structure. However, thecurrent dispersion effect may be sufficiently ensured by the conductivevia v formed in the inside of the second-conductivity type semiconductorlayer 801.

The high resistance part 808 is formed on the side surface of the lightemitting structure and functions to protect the light emittingstructure, in particular, the active layer 802, from the outside,thereby improving the electrical reliability of the semiconductor lightemitting device. Since the active layer 802 exposed to the outside mayact as a current leakage path during the operation of the semiconductorlight emitting device 800, current leakage may be prevented by formingthe high resistance part 808 with a relatively high electric resistanceon the side surface of the light emitting structure. In this case, thehigh resistance part 808 may be formed by ion implantation.Specifically, when ions accelerated by a particle accelerator areinjected into the light emitting structure, the crystals of thesemiconductor layer constituting the light emitting structure aredamaged and electrical resistance is increased. Since the injected ionsmay be recovered by a thermal treatment, ions having a relatively largeparticle size may be used so that they are not recovered during ageneral thermal treatment temperature of the semiconductor layer. Forexample, ions of atoms such as Ar, C, N, Kr, Xe, Cr, O, Fe, or Ti may beused as the ions which are injected into the light emitting structure.

FIGS. 38 and 39 are schematic cross-sectional views of a semiconductorlight emitting device according to a modified embodiment of the presentinvention. In the case of the semiconductor light emitting device 800-1illustrated in FIG. 38, the side surface of the light emitting structureis inclined with respect to the first-conductivity type contact layer804. Specifically, the side surface of the light emitting structure isinclined toward the top surface of the light emitting structure. Asdescribed above, the inclined shape of the semiconductor light structuremay be naturally formed by a process of etching the light emittingstructure in order to expose the first-conductivity type contact layer804. In the case of the light emitting device 800-2 illustrated in FIG.39, an uneven structure is formed on the top surface of the lightemitting structure provided in the embodiment of FIG. 38, specifically,the top surface of the second-conductivity type semiconductor layer 801.Although the uneven structure may be formed by a dry etching process ora wet etching process, it is preferable that the uneven structure havingan irregular size, shape and period is formed by a wet etching process.Such an uneven structure may increase the probability light incidentfrom the active layer 802 be emitted the outside. Meanwhile, themodified embodiments of FIGS. 38 and 39 may also be applied to otherembodiments of FIGS. 40 through 42.

FIG. 40 is a schematic cross-sectional view of a semiconductor lightemitting device according to another embodiment of the presentinvention. Referring to FIG. 40, the semiconductor light emitting device900 according to this embodiment of the present invention includes afirst-conductivity type contact layer 904 on a conductive substrate 907.A light emitting structure is formed on the first-conductivity typecontact layer 904. The light emitting structure includes afirst-conductivity type semiconductor layer 903, an active layer 902,and a second-conductivity type semiconductor layer 901. A highresistance part 908 is formed on the side surface of the light emittingstructure by ion implantation. A structural difference from theforegoing embodiment is that the conductive substrate 907 iselectrically connected to the first-conductivity type semiconductorlayer 903, not the second-conductivity type semiconductor layer 901.Hence, the first-conductivity type contact layer 904 is not necessarilyrequired. In this case, the first-conductivity type semiconductor layer903 and the conductive substrate 907 may directly contact each other.

The second-conductivity type semiconductor layer 901 and the conductivevia v connected to the inside thereof pass through the active layer 902,the first-conductivity type semiconductor layer 903, and thefirst-conductivity type contact layer 904 and are electrically connectedto a second-conductivity type electrode 909. The second-conductivitytype electrode 909 may include an electrical connection part whichextends from the conductive via v to the lateral direction of the lightemitting structure and is exposed to the outside. An electrode pad 905may be formed on the electrical connection part. In this case, aninsulator 906 is formed for electrically separating thesecond-conductivity type electrode 909 and the conductive via v from theactive layer 902, the first-conductivity type semiconductor layer 903,the first-conductivity type contact layer 904, and the conductivesubstrate 907.

FIG. 41 is a schematic plan view of a semiconductor light emittingdevice according to another embodiment of the present invention, andFIG. 42 is a schematic cross-sectional view taken along line B-B′ ofFIG. 41. Like the embodiment of FIGS. 35 through 37, the semiconductorlight emitting device according to this embodiment of the presentinvention includes a first-conductivity type contact layer 804′ on aconductive substrate 807′. A light emitting structure is formed on thefirst-conductivity type contact layer 804′. The light emitting structureincludes a first-conductivity type semiconductor layer 803′, an activelayer 802′, and a second-conductivity type semiconductor layer 801′. Ahigh resistance part 808′ is formed on the side surface of the lightemitting structure by ion implantation. In addition, thefirst-conductivity type contact layer 804′ is electrically separatedfrom the conductive substrate 807′. To this end, an insulator 806′ isdisposed between the first-conductivity type contact layer 804′ and theconductive substrate 807′. In this embodiment, the light emittingstructure on the conductive substrate 807′ is divided into a pluralityof structures. The divided light emitting structures increase the lightscattering effect, thereby improving the light extraction efficiency. Inorder to ensure a sufficient external area, the light emitting structuremay be formed in a hexagonal shape, in a top view, as illustrated inFIG. 41. In this case, as the interval between the light emittingstructures increases, the area of the active layer 802′ itself isreduced, causing a degradation of luminous efficiency. Thus, the dividedlight emitting structures may be arranged as closely as possible. Asdescribed above, when an etching process is performed for dividing thelight emitting structure, it is necessary to protect the side surface ofthe light emitting structure. Therefore, the high resistance part 808′may be formed on the side surfaces of the divided light emittingstructures by ion implantation.

Hereinafter, a method of manufacturing the semiconductor light emittingdevice having the above-described structure will be described in detail.

FIGS. 43 through 51 are cross-sectional views illustrating a method ofmanufacturing the semiconductor light emitting device. Specifically,FIGS. 43 through 51 illustrate a method of manufacturing thesemiconductor light emitting device described above with reference toFIGS. 35 through 37.

Referring to FIG. 43, a light emitting structure is formed on asemiconductor growth substrate B by sequentially growing asecond-conductivity type semiconductor layer 801, an active layer 802,and a first-conductivity type semiconductor layer 803 through asemiconductor layer growth process, e.g., MOCVD, MBE, HVPE, etc. Thesemiconductor growth substrate B may be formed of sapphire, SiC,MgAl₂O₄, MaO, LiAlO₂, LiGaO₂, or GaN. Sapphire is a crystal having aHexa-Rhombo R3c symmetry, and has a lattice constant of 13,001 Å along ac-axis and a lattice constant of 4,758 Å along an a-axis. Sapphire has aC(0001) plane, an A(1120) plane, and an R(1102) plane. In this case, theC plane is mainly used as a nitride growth substrate because itfacilitates the growth of a nitride thin film and is stable at a hightemperature.

Referring to FIG. 44, a first-conductivity type contact layer 804 isformed on the first-conductivity type semiconductor layer 803. Thefirst-conductivity type contact layer 804 may be formed of Ag, Ni, Al,Rh, Pd, Ir, Ru, Mg, Zn, Pt, or Au, considering the light reflectionfunction and the ohmic contact function with the first-conductivity typesemiconductor layer 803. A known process, e.g., a sputtering process ora deposition process, may be appropriately used. Referring to FIG. 45,grooves are formed in the first-conductivity type contact layer 804 andthe light emitting structure. Specifically, the grooves are filled witha conductive material in a subsequent process to form a conductive viawhich is electrically connected to the second-conductivity typesemiconductor layer 801. The grooves pass through the first-conductivitytype contact layer 804, the first-conductivity type semiconductor layer803, and the active layer 802, and the second-conductivity typesemiconductor layer 801 is exposed at the bottom surfaces of thegrooves. The process of forming the grooves in FIG. 45 may also beperformed using a known etching process, e.g., ICP-RIE.

Referring to FIG. 46, a material such as SiO₂, SiO_(x)N_(y), orSi_(x)N_(y) is deposited to form an insulator 806 which covers the topsurface of the first-conductivity type contact layer 804 and thesidewalls of the grooves. In this case, at least a portion of thesecond-conductivity type semiconductor layer 801 corresponding to thebottom surface of the grooves needs to be exposed. Hence, the insulator806 may be formed so as not to cover the entire bottom surfaces of thegrooves.

Referring to FIG. 47, a conductive material is formed on the inside ofthe grooves and the insulator 806 to form a conductive via v and aconductive substrate 807. Accordingly, the conductive substrate 807 isconnected to the conductive via v which is connected to thesecond-conductivity type semiconductor layer 801. The conductivesubstrate 807 may be formed of a material including any one of Au, Ni,Al, Cu, W, Si, Se, and GaAs. The conductive substrate 807 may be formedusing a plating process, a sputtering process, a deposition process, ora bonding process. In this case, the conductive via v and the conductivesubstrate 807 may be formed of the same material. However, in somecases, the conductive via v and the conductive substrate 807 may beformed of different materials and may be formed by separate processes.For example, after the conductive via v is formed by a depositionprocess, the conductive substrate 807 having already been formed may bebonded with the light emitting structure.

Referring to FIG. 48, the semiconductor growth substrate B is removed toexpose the second-conductivity type semiconductor layer 801. In thiscase, the semiconductor growth substrate B may be removed using a laserlift-off process or a chemical lift-off process. FIG. 48 illustrates thesemiconductor light emitting device when the semiconductor growthsubstrate B is removed. Also, FIG. 48 is turned by 180 degrees comparedwith FIG. 47.

Referring to FIG. 49, a portion of the light emitting structure, i.e.,the first-conductivity type semiconductor layer 803, the active layer802, and the second-conductivity type semiconductor layer 801, isremoved to expose the first-conductivity type contact layer 804. This isdone for applying the electric signal through the exposedfirst-conductivity type contact layer 804. As described above, theprocessing of removing the light emitting structure may be used todivide the light emitting structure into a plurality of structures.Meanwhile, although not illustrated, a process of forming an electrodepad on the exposed region of the first-conductivity type contact layer804 may be further performed. In order to expose the first-conductivitytype contact layer 804, the light emitting structure may be etched usingICP-RIE or the like. In this case, as illustrated in FIG. 50, an etchstop layer 809 may be formed in advance within the light emittingstructure in order to prevent the material of the first-conductivitytype contact layer 804 from being moved and attached to the side surfaceof the light emitting structure during the etching process.

Referring to FIG. 51, a high resistance part 808 having an electricalinsulation characteristic is formed on the side surface of the lightemitting structure. The high resistance part 808 corresponds to a regionwhere crystals are damaged by ions injected into the side surface of thesemiconductor layer constituting the light emitting structure. In thiscase, since the injected ions may be recovered by a thermal treatment,ions having a relatively large particle size may be used so that theyare not recovered during a general thermal treatment temperature of thesemiconductor layer. For example, ions of atoms such as Ar, C, N, Kr,Xe, Cr, O, Fe, or Ti may be used as the ions which are injected into thelight emitting structure.

FIGS. 52 through 55 are cross-sectional views illustrating a method ofmanufacturing a semiconductor light emitting device according to anotherembodiment of the present invention. Specifically, FIGS. 52 through 55illustrate a method of manufacturing the semiconductor light emittingdevice described above with reference to FIG. 40. In this case, theprocesses described above with reference to FIGS. 43 through 45 may beemployed in this embodiment. Hereinafter, a subsequent process afterforming the grooves in the first-conductivity type contact layer 904 andthe light emitting structure will be described below.

Referring to FIG. 52, a material such as SiO₂, SiO_(x)N_(y), orSi_(x)N_(y) is deposited to form an insulator 906 which covers the topsurface of the first-conductivity type contact layer 904 and thesidewalls of the grooves. The insulator 906 may be referred to as afirst insulator in order to distinguish from an insulator which isformed to cover a second-conductivity type electrode 909 in a subsequentprocess. A difference from the foregoing embodiment is that theinsulator 906 is not formed on the entire top surface of thefirst-conductivity type contact layer 904 because the conductivesubstrate 907 and the first-conductivity type contact layer 904 must beelectrically connected together. That is, the insulator 906 may beformed by previously considering a portion of the top surface of thefirst-conductivity type contact layer 904; specifically, a region wherethe second-conductivity type electrode 909 connected to thesecond-conductivity type semiconductor layer 901 will be formed.

Referring to FIG. 53, a conductive material is formed on the inside ofthe grooves and the insulator 906 to form the second-conductivity typeelectrode 909. Accordingly, the second-conductivity type electrode 909may include a conductive via v which is connected to thesecond-conductivity type semiconductor layer 901. At this step, theinsulator 906 is previously formed in a region where thesecond-conductivity type electrode 909 will be formed. Thus, thesecond-conductivity type electrode 909 may be formed along the insulator906. In particular, the second-conductivity type electrode 909 mayextend from the conductive via v in a horizontal direction so that it isexposed to the outside and functions as an electrical connection part.

Referring to FIG. 54, an insulator 906 is formed to cover thesecond-conductivity type electrode 909, and a conductive substrate 907is formed on the insulator 906 so that it is electrically connected tothe first-conductivity type contact layer 904. In this case, theinsulator 906 formed in this process may be referred to as a secondinsulator. The second insulator and the first insulator may constitute asingle insulation structure. Due to this process, thesecond-conductivity type electrode 909 may be electrically separatedfrom the first-conductivity type contact layer 904, the conductivesubstrate 907, and so on. Referring to FIG. 55, the semiconductor growthsubstrate B is removed to expose the second-conductivity typesemiconductor layer 901. Although not illustrated, a process of removinga portion of the light emitting structure to expose thesecond-conductivity type electrode 909 and a process of forming a highresistance part 908 by ion implantation into the side surface of thelight emitting structure may be performed using the above-describedprocesses.

A semiconductor light emitting device according to another embodiment ofthe present invention will be described below with reference to FIGS. 56through 75.

FIG. 56 is a schematic perspective view of a semiconductor lightemitting device according to this embodiment of the present invention.FIG. 57 is a schematic plan view illustrating a second-conductivity typesemiconductor layer of the semiconductor light emitting device of FIG.56. FIG. 58 is a schematic cross-sectional view taken along line A-A′ ofFIG. 57. The semiconductor light emitting device 1000 according to thisembodiment of the present invention includes a first-conductivity typecontact layer 1004 on a conductive substrate 1007. A light emittingstructure is formed on the first-conductivity type contact layer 1004.The light emitting structure includes a first-conductivity typesemiconductor layer 1003, an active layer 1002, and asecond-conductivity type semiconductor layer 1001. An undopedsemiconductor layer 1008 is formed on the second-conductivity typesemiconductor layer 1001. Since the undoped semiconductor layer 1008 hasan uneven top surface, it is possible to improve the external extractionefficiency of light emitted from the active layer 1002. Thefirst-conductivity type contact layer 1004 is electrically separatedfrom the conductive substrate 1007. To this end, an insulator 1006 isdisposed between the first-conductivity type contact layer 1004 and theconductive substrate 1007.

In this embodiment, the first-conductivity type semiconductor layer 1003and the second-conductivity type semiconductor layer 1001 may be ap-type semiconductor layer and an n-type semiconductor layer,respectively, and may be formed of nitride semiconductors. In thisembodiment, the first-conductivity type and the second-conductivity typemay be understood as, but are not limited to, p-type and n-typesemiconductors, respectively. The first-conductivity type semiconductorlayer 1003 and the second-conductivity type semiconductor layer 1001have a composition of Al_(x)In_(y)Ga_((1-x-y))N (where 0≦x≦1, 0≦y≦1,0≦x+y≦1), e.g., GaN, AlGaN, InGaN, etc. The active layer 1002 formedbetween the first-conductivity type semiconductor layer 1003 and thesecond-conductivity type semiconductor layer 1001 emits light having apredetermined energy due to the recombination of electrons and holes andmay have a multiple quantum well (MQW) structure in which a quantum welllayer and a quantum barrier layer are alternately stacked. For example,an InGaN/GaN structure may be used for the multiple quantum wellstructure.

The first-conductivity type contact layer 1004 may reflect light emittedfrom the active layer 1002 toward the top of the semiconductor lightemitting device 1000, i.e., the second-conductivity type semiconductorlayer 1001. Furthermore, the first-conductivity type contact layer 1004may form an ohmic contact with the first-conductivity type semiconductorlayer 1003. Considering this function, the first-conductivity typecontact layer 1004 may include Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt,or Au. In this case, although not illustrated in detail, thefirst-conductivity type contact layer 1004 may have a structure capableof improving the reflection efficiency. Specifically, thefirst-conductivity type contact layer 1004 may have a structureincluding at least one of Al, Ag, Ni/Ag, Zn/Ag, Ni/Al, Zn/Al, Pd/Ag,Pd/Al, Ir/Ag, Ir/Au, Pt/Ag, Pt/Al, Ni/Ag/Pt, and combinations thereof.In this embodiment, a portion of the first-conductivity type contactlayer 1004 may be exposed to the outside. As illustrated, the exposedregion may be a region where the light emitting structure is not formed.The exposed region of the first-conductivity type contact layer 1004corresponds to an electrical connection part for applying an electricsignal, and an electrode pad 1005 may be formed on the exposed region ofthe first-conductivity type contact layer 1004.

As will be described later, the conductive substrate 1007 functions as asupport body which supports the light emitting structure in a laserlift-off process or the like. The conductive substrate 1007 may includeat least one material selected from the group consisting of Au, Ni, Al,Cu, W, Si, Se, and GaAs, for example, pure Cu or AlSi which is acombination of Si and Al. In this case, the conductive substrate 1007may be formed using a plating method or a bonding method according tothe selected material. In this embodiment, the conductive substrate 1007is electrically connected to the second-conductivity type semiconductorlayer 1001. Accordingly, the electric signal may be applied to thesecond-conductivity type semiconductor layer 1001 through the conductivesubstrate 1007. To this end, as illustrated in FIGS. 57 and 58, it isnecessary to provide a conductive via v which extends from theconductive substrate 1007 and is electrically connected to thesecond-conductivity type semiconductor layer 1001.

The conductive via v is connected to the inside of thesecond-conductivity type semiconductor layer 1001. To reduce the contactresistance, the number, shape and pitch of the conductivity via v andits contact area with the second-conductivity type semiconductor layer1001 may be appropriately adjusted. In this case, since the conductivevia v needs to be electrically separated from the active layer 1002, thefirst-conductivity type semiconductor layer 1003, and thefirst-conductivity type contact 1004, an insulator 1006 is formedbetween the conductivity via v and the respective layers 1002, 1003 and1004. The insulator 1006 may be formed of any material if it has anelectrical insulation characteristic. Preferably, the insulator 1009 isformed of a material which absorbs low amounts of light. For example,the insulator 1006 may be formed of silicon oxide, silicon nitride, oranother insulating material, e.g., SiO₂, SiO_(x)N_(y), Si_(x)N_(y), etc.

As described above, in this embodiment, the conductive substrate 1007 iselectrically connected to the second-conductivity type semiconductorlayer 1001 through the conductive via v, and it is unnecessary toseparately form an electrode on the top surface of thesecond-conductivity type semiconductor layer 1001. Accordingly, theamount of light emitted to the top surface of the second-conductivitytype semiconductor layer 1001 may increase. In this case, since theconductive via v is formed at a portion of the active layer 1002, thelight emitting region is reduced. However, since no electrode is formedon the top surface of the second-conductivity type semiconductor layer1001, the light extraction efficiency may be further improved.Meanwhile, in the semiconductor light emitting device 1000 according tothis embodiment of the present invention, since no electrode is disposedon the top surface of the second-conductivity type semiconductor layer1001, the entire electrode arrangement is similar to the horizontalelectrode structure rather than the vertical electrode structure.However, the current dispersion effect may be sufficiently ensured bythe conductive via v formed in the inside of the second-conductivitytype semiconductor layer 1001.

An undoped semiconductor layer 1008 is formed on the top surface of thesecond-conductivity type semiconductor layer 1001. As will be describedlater, the undoped semiconductor layer 1008 is used as a buffer layerbefore the growth of the semiconductor layer constituting the lightemitting structure. In this case, the term “undoped” means that noimpurity doping process is performed on the semiconductor layer. Theimpurity concentration originally existing in the semiconductor layer isincluded. For example, when a nitride gallium semiconductor is grownusing MOCVD, an impurity concentration of approximately 10¹⁶-10¹⁸/cm² isincluded, even though Si used as dopant is not intended. In thisembodiment, since it is unnecessary to form an electrode on the topsurface of the second-conductivity type semiconductor layer 1001, theundoped layer 1008 is not removed. Accordingly, the undopedsemiconductor layer 1008 may be formed to cover the entire top surfaceof the second-conductivity type semiconductor layer 1001. Furthermore,the probability that light incident from the active layer 1002 will beemitted to the outside is increased by forming the uneven structure inthe undoped semiconductor layer 1008. Although the structure where theuneven pattern is formed only on the undoped semiconductor layer 1008has been described above, the uneven pattern may also be formed to aportion of the second-conductivity type semiconductor layer 1001,depending on an etching condition.

If the undoped semiconductor layer 1008 is removed and the unevenstructure is formed on the second-conductivity type semiconductor layer1001, a portion of the second-conductivity type semiconductor layer 1001may be damaged. In particular, if the process of forming the unevenstructure is not controlled precisely, the thickness of thesecond-conductivity type semiconductor layer 1001 may not be uniformaccording to product. In this embodiment, in order to solve thisproblem, the electrode connection structure of the second-conductivitytype semiconductor layer 1001 is formed at the lower portion through theinside of the second-conductivity type semiconductor layer 1001, and theuneven pattern is formed on the undoped semiconductor layer 1008 whichis not removed.

FIGS. 59 and 60 are schematic cross-sectional views illustratingmodified embodiments of the semiconductor light emitting device of FIG.56. In the case of a semiconductor light emitting device 1000-1illustrated in FIG. 59, the side surface of the light emitting structureis inclined with respect to the first-conductivity type contact layer1004. Specifically, the side surface of the light emitting structure isinclined toward the top surface of the light emitting structure. Asdescribed above, the inclined shape of the semiconductor light structuremay be naturally formed by a process of etching the light emittingstructure in order to expose the first-conductivity type contact layer1004. In the case of the light emitting device 1000-2 illustrated inFIG. 60, a passivation layer 1009 is formed to cover the side surface ofthe light emitting structure illustrated in FIG. 59. The passivationlayer 1009 protects the light emitting structure, specifically theactive layer 1002, from the outside. The passivation layer 1009 may beformed of silicon oxide or silicon nitride, e.g., SiO₂, SiO_(x)N_(y), orSi_(x)N_(y) and may be approximately 0.1-2 μm in thickness.

The active layer 1002 exposed to the outside may act as a currentleakage path during the operation of the semiconductor light emittingdevice 1000. However, such a problem can be prevented by forming thepassivation layer 1009 on the sides of the light emitting structure.Considering this, as illustrated in FIG. 60, the passivation layer 1009may extend on the exposed top surface of the first-conductivity typecontact layer 1004. Meanwhile, the modified embodiments of FIGS. 59 and60 may also be applied to other embodiments of FIGS. 61 and 62.

FIG. 61 is a schematic cross-sectional view of a semiconductor lightemitting device according to another embodiment of the presentinvention. Referring to FIG. 61, the semiconductor light emitting device1100 according to this embodiment of the present invention includes afirst-conductivity type contact layer 1104 on a conductive substrate1107. A light emitting structure is formed on the first-conductivitytype contact layer 1104. The light emitting structure includes afirst-conductivity type semiconductor layer 1103, an active layer 1102,and a second-conductivity type semiconductor layer 1101. An undopedsemiconductor layer 1108 is formed on the second-conductivity typesemiconductor layer 1101. The undoped semiconductor layer 1108 has anuneven top surface. In addition, the first-conductivity type contactlayer 1104 is electrically separated from the conductive substrate 1107.To this end, an insulator 1106 is disposed between thefirst-conductivity type contact layer 1104 and the conductive substrate1107.

Unlike the foregoing embodiment in which the electrical connection partof the first-conductivity type contact layer 1004 is formed in the edgeportion of the light emitting structure in a top plan view, theelectrical connection part of the first-conductivity type contact layer1104 according to this embodiment is formed in a region corresponding tothe center portion of the light emitting structure in a top plan view.As such, if necessary, the position of the region where thefirst-conductivity type contact layer 1104 is exposed may be changed. Anelectrode pad 1105 is formed in the electrical connection part of thefirst-conductivity type contact layer 1104.

FIG. 62 is a schematic cross-sectional view of a semiconductor lightemitting device according to another embodiment of the presentinvention. Referring to FIG. 62, the semiconductor light emitting device1200 according to this embodiment of the present invention includes afirst-conductivity type contact layer 1204 on a conductive substrate1207. A light emitting structure is formed on the first-conductivitytype contact layer 1204. The light emitting structure includes afirst-conductivity type semiconductor layer 1203, an active layer 1202,and a second-conductivity type semiconductor layer 1201. An undopedsemiconductor layer 1208 is formed on the light emitting structure,i.e., the second-conductivity type semiconductor layer 1201. Astructural difference from the previous embodiment is that theconductive substrate 1207 is electrically connected to thefirst-conductivity type semiconductor layer 1203, not thesecond-conductivity type semiconductor layer 1201. Therefore, thefirst-conductivity type semiconductor layer 1203 is not necessarilyrequired. In this case, the first-conductivity type semiconductor layer1203 and the conductive substrate 1207 may directly contact each other.

The second-conductivity type semiconductor layer 1201 and the conductivevia v connected to the inside thereof pass through the active layer1202, the first-conductivity type semiconductor layer 1203, and thefirst-conductivity type contact layer 1204 and are electricallyconnected to a second-conductivity type electrode 1209. Thesecond-conductivity type electrode 1209 may include an electricalconnection part which extends from the conductive via v to the lateraldirection of the light emitting structure and is exposed to the outside.An electrode pad 1205 may be formed on the electrical connection part.In this case, an insulator 1206 is formed for electrically separatingthe second-conductivity type electrode 1209 and the conductive via vfrom the active layer 1202, the first-conductivity type semiconductorlayer 1203, the first-conductivity type contact layer 1204, and theconductive substrate 1207.

Hereinafter, a method of manufacturing the semiconductor light emittingdevice having the above-described structure will be described in detail.

FIGS. 63 through 71 are cross-sectional views illustrating a method ofmanufacturing the semiconductor light emitting device according anembodiment of the present invention. Specifically, FIGS. 63 through 71illustrate a method of manufacturing the semiconductor light emittingdevice described above with reference to FIGS. 56 through 58.

Referring to FIG. 63, a light emitting structure is formed on asemiconductor growth substrate B by sequentially growing a buffer layer1008, a second-conductivity type semiconductor layer 1001, an activelayer 1002, and a first-conductivity type semiconductor layer 1003through a semiconductor layer growth process, e.g., MOCVD, MBE, HVPE,etc. In this case, although the light emitting structure is defined as astructure including the second-conductivity type semiconductor layer1001, the active layer 1002, and the first-conductivity typesemiconductor layer 1003 in a structural view, but the buffer layer 1008may be considered as an element of the light emitting structure in viewof the growth and etching process. Therefore, hereinafter, the lightemitting structure is defined as a structure including the buffer layer1008, the second-conductivity type semiconductor layer 1001, the activelayer 1002, and the first-conductivity type semiconductor layer 1003.

The semiconductor growth substrate B may be formed of sapphire, SiC,MgAl₂O₄, MaO, LiAlO₂, LiGaO₂, or GaN. Sapphire is a crystal having aHexa-Rhombo R3c symmetry, and has a lattice constant of 13,001 Å along ac-axis and a lattice constant of 4,758 Å along an a-axis. Sapphire has aC(0001) plane, an A(1120) plane, and an R(1102) plane. In this case, theC plane is mainly used as a nitride growth substrate because itfacilitates the growth of a nitride thin film and is stable at a hightemperature. As described above, the buffer layer 1008 may be providedwith an undoped semiconductor layer formed of nitride, and may reducethe lattice defect in the light emitting structure grown thereupon.

Referring to FIG. 64, a first-conductivity type contact layer 1004 isformed on the first-conductivity type semiconductor layer 1003. Thefirst-conductivity type contact layer 1004 may be formed of Ag, Ni, Al,Rh, Pd, Ir, Ru, Mg, Zn, Pt, or Au, considering the light reflectionfunction and the ohmic contact function with the first-conductivity typesemiconductor layer 1003. A known process, e.g., a sputtering process ora deposition process, may be appropriately used. Referring to FIG. 65,grooves are formed in the first-conductivity type contact layer 1004 andthe light emitting structure. Specifically, the grooves are filled witha conductive material in a subsequent process to form a conductive viawhich is electrically connected to the second-conductivity typesemiconductor layer 1001. The grooves pass through thefirst-conductivity type contact layer 1004, the first-conductivity typesemiconductor layer 1003, and the active layer 1002, and thesecond-conductivity type semiconductor layer 1001 is exposed at thebottom surfaces of the grooves. The process of forming the grooves inFIG. 65 may also be performed using a known etching process, e.g.,ICP-RIE.

Referring to FIG. 66, a material such as SiO₂, SiO_(x)N_(y), orSi_(x)N_(y) is deposited to form an insulator 1006 which covers the topsurface of the first-conductivity type contact layer 1004 and thesidewalls of the grooves. In this case, at least a portion of thesecond-conductivity type semiconductor layer 1001 corresponding to thebottom surface of the grooves needs to be exposed. Hence, the insulator1006 may be formed so as not to cover the entire bottom surfaces of thegrooves.

Referring to FIG. 67, a conductive material is formed on the inside ofthe grooves and the insulator 1006 to form a conductive via v and aconductive substrate 1007. Accordingly, the conductive substrate 1007 isconnected to the conductive via v which is connected to thesecond-conductivity type semiconductor layer 1001. The conductivesubstrate 1007 may be formed of a material including any one of Au, Ni,Al, Cu, W, Si, Se, and GaAs. The conductive substrate 807 may be formedusing a plating process, a sputtering process, a deposition process, ora bonding process. In this case, the conductive via v and the conductivesubstrate 1007 may be formed of the same material. However, in somecases, the conductive via v and the conductive substrate 1007 may beformed of different materials and may be formed by separate processes.For example, after the conductive via v is formed by a depositionprocess, the conductive substrate 1007 having already been formed may bebonded with the light emitting structure.

Referring to FIG. 68, the semiconductor growth substrate B is removed toexpose the buffer layer 1008. In this case, the semiconductor growthsubstrate B may be removed using a laser lift-off process or a chemicallift-off process. FIG. 68 illustrates the semiconductor light emittingdevice when the semiconductor growth substrate B is removed. Also, FIG.68 is turned by 180 degrees as compared with FIG. 67.

Referring to FIG. 69, a portion of the light emitting structure, i.e.,the first-conductivity type semiconductor layer 1003, the active layer1002, and the second-conductivity type semiconductor layer 1001, isremoved to expose the first-conductivity type contact layer 1004. Thisis done for applying the electric signal through the exposedfirst-conductivity type contact layer 1004. Although not illustrated, aprocess of forming an electrode pad on the exposed region of thefirst-conductivity type contact layer 1004 may be further performed. Inorder to expose the first-conductivity type contact layer 1004, thelight emitting structure may be etched using ICP-RIE or the like. Inthis case, as illustrated in FIG. 70, an etch stop layer 1010 may beformed in advance within the light emitting structure in order toprevent the material of the first-conductivity type contact layer 1004from being moved and attached to the side surface of the light emittingstructure during the etching process. Furthermore, in order to furtherensure the insulation structure, a passivation layer 1009 of FIG. 60 maybe formed on the side surface of the light emitting structure afteretching the light emitting structure.

Referring to FIG. 71, an uneven structure is formed in the buffer layer1008. In this case, the region where the uneven structure is mainlyformed is the top surface of the buffer layer 1008 which is exposed bythe removal of the semiconductor growth substrate B. The unevenstructure may improve light extraction efficiency. In this case, theuneven structure may be formed using a dry etching process or a wetetching process. The uneven structure having facets of an irregularsize, shape and period may be formed using a wet etching process. Inthis embodiment, even though the buffer layer 1008 having a lowelectrical conductivity is not removed, there is no problem in applyingan electric signal to the first-conductivity type semiconductor layer1001. By forming the uneven structure in the buffer layer 1008, theuniform thickness of the first-conductivity type semiconductor layer1001 may be ensured.

FIGS. 72 through 75 are cross-sectional views illustrating a method ofmanufacturing a semiconductor light emitting device according to anotherembodiment of the present invention. Specifically, FIGS. 72 through 75illustrate a method of manufacturing the semiconductor light emittingdevice described above with reference to FIG. 62. In this case, theprocesses described above with reference to FIGS. 63 through 65 may beemployed in this embodiment. Hereinafter, a subsequent process afterforming the grooves in the first-conductivity type contact layer 1204and the light emitting structure will be described below.

Referring to FIG. 72, a material such as SiO₂, SiO_(x)N_(y), orSi_(x)N_(y) is deposited to form an insulator 1206 which covers the topsurface of the first-conductivity type contact layer 1204 and thesidewalls of the grooves. The insulator 1206 may be referred to as afirst insulator in order to distinguish it from an insulator which isformed to cover a second-conductivity type electrode 1209 in asubsequent process. A difference from the foregoing embodiment is thatthe insulator 1206 is not formed on the entire top surface of thefirst-conductivity type contact layer 1204 because the conductivesubstrate 1207 and the first-conductivity type contact layer 1204 mustbe electrically connected together. That is, the insulator 1206 may beformed by previously considering a portion of the top surface of thefirst-conductivity type contact layer 1204; specifically, a region wherethe second-conductivity type electrode 1209 connected to thesecond-conductivity type semiconductor layer 1201 will be formed.

Referring to FIG. 73, a conductive material is formed on the inside ofthe grooves and the insulator 1206 to form the second-conductivity typeelectrode 1209. Accordingly, the second-conductivity type electrode 1209may include a conductive via v which is connected to thesecond-conductivity type semiconductor layer 1201. At this step, theinsulator 1206 is previously formed in a region where thesecond-conductivity type electrode 1209 will be formed. Thus, thesecond-conductivity type electrode 1209 may be formed along theinsulator 1206. In particular, the second-conductivity type electrode1209 may extend from the conductive via v in a horizontal direction sothat it is exposed to the outside and functions as an electricalconnection part.

Referring to FIG. 74, an insulator 1206 is formed to cover thesecond-conductivity type electrode 1209, and a conductive substrate 1207is formed on the insulator 1206 so that it is electrically connected tothe first-conductivity type contact layer 1204. In this case, theinsulator 1206 formed in this process may be referred to as a secondinsulator. The second insulator and the first insulator may constitute asingle insulation structure. Due to this process, thesecond-conductivity type electrode 1209 may be electrically separatedfrom the first-conductivity type contact layer 1204, the conductivesubstrate 1207, and so on. Referring to FIG. 75, the semiconductorgrowth substrate B is removed to expose the buffer layer 1208. Althoughnot illustrated, a process of removing a portion of the light emittingstructure to expose the second-conductivity type electrode 1209 and aprocess of forming an uneven structure in the buffer layer 1208 may beperformed using the above-described processes.

A semiconductor light emitting device according to another embodiment ofthe present invention will be described below with reference to FIGS. 76through 89.

FIG. 76 is a schematic cross-sectional view of a semiconductor lightemitting device according to another embodiment of the presentinvention, and FIG. 77 is a circuit diagram of the semiconductor lightemitting device of FIG. 76. Referring to FIG. 76, the semiconductorlight emitting device 1300 according to this embodiment of the presentinvention includes a plurality of light emitting structures C1 and C2 ona substrate 1306. The light emitting structures C1 and C2 areelectrically connected together. Hereinafter, the two light emittingstructures will be referred to as a first light emitting structure C1and a second light emitting structure C2, respectively. Each of thefirst and second light emitting structures C1 and C2 includes afirst-conductivity type semiconductor layer 1303, an active layer 1302,and a second-conductivity type semiconductor layer 1301, which arestacked in sequence. Also, the first and second light emittingstructures C1 and C2 include a first electrical connection part 1304 anda second electrical connection part 1307 for electrical connection.

The first electrical connection part 1304 is formed under thefirst-conductivity type semiconductor layer 1303 and may perform anohmic contact and light reflection function as well as the electricalconnection function. The second electrical connection part 1307 iselectrically connected to the second-conductivity type semiconductorlayer 1301. The second electrical connection part 1307 includes aconductive via v passing through the first electrical connection part1304, the first-connectivity type semiconductor layer 1303, and theactive layer 1302, and thus it may be connected to thesecond-conductivity type semiconductor layer 1301. The second electricalconnection part of the first light emitting structure C1, i.e., theconductive via v is electrically connected to the first electricalconnection part 1304 of the second light emitting structure C2 areelectrically connected together through the substrate 1306. To this end,the substrate 1306 is formed of a conductive material. Due to such anelectrical connection structure, the semiconductor light emittingstructure 1300 is operable even though an external AC voltage isapplied.

In this embodiment, the first-conductivity type semiconductor layer 1303and the second-conductivity type semiconductor layer 1301 may be ap-type semiconductor layer and an n-type semiconductor layer,respectively, and may be formed of nitride semiconductors. In thisembodiment, the first-conductivity type and the second-conductivity typemay be understood as, but are not limited to, p-type and n-type,respectively. The first-conductivity type semiconductor layer 1303 andthe second-conductivity type semiconductor layer 1301 have a compositionof Al_(x)In_(y)Ga_((1-x-y))N (where 0≦x≦1, 0≦y≦1, 0≦x+y≦1), e.g., GaN,AlGaN, InGaN, etc. The active layer 1302 formed between thefirst-conductivity type semiconductor layer 1303 and thesecond-conductivity type semiconductor layer 1301 emits light having apredetermined energy due to the electron/hole recombination and may havea multiple quantum well (MQW) structure in which a quantum well layerand a quantum barrier layer are alternately stacked. For example, anInGaN/GaN structure may be used for the multiple quantum well structure.

As described above, the first electrical connection part 1304 mayreflect light emitted from the active layer 1302 toward the top of thesemiconductor light emitting device 1300, i.e., the second-conductivitytype semiconductor layer 1301. Furthermore, the first electricalconnection part 104 may form an ohmic contact with thefirst-conductivity type semiconductor layer 1303. Considering thisfunction, the first electrical connection part 1304 may include Ag, Ni,Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, or Au. In this case, although notillustrated in detail, the first electrical connection part 1304 mayhave a structure capable of improving reflection efficiency.Specifically, the first electrical connection part 1304 may have astructure including at least one of Al, Ag, Ni/Ag, Zn/Ag, Ni/Al, Zn/Al,Pd/Ag, Pd/Al, Ir/Ag, Ir/Au, Pt/Ag, Pt/Al, Ni/Ag/Pt, and combinationsthereof.

In manufacturing the semiconductor light emitting device 1300, thesubstrate 1306 functions as a support body which supports the first andsecond light structures C1 and C2 in a laser lift-off process or thelike. A conductive substrate may be used for the electrical connectionof the first and second light emitting structures C1 and C2. Thesubstrate 1306 may be formed of a conductive material including any oneof Au, Ni, Al, Cu, W, Si, Se, and GaAs, for example, pure Cu or AlSi, acombination of Si and Al. In this case, the substrate 1306 may be formedusing a plating method, a deposition method, or a bonding methodaccording to the selected material.

The conductive via v provided in the second electrical connection part1307 is connected to the inside of the second-conductivity typesemiconductor layer 1301. To reduce the contact resistance, the number,shape and pitch of the conductivity via v and its contact area with thesecond-conductivity type semiconductor layer 1301 may be appropriatelyadjusted. In this case, since the conductive via v needs to beelectrically separated from the active layer 1302, thefirst-conductivity type semiconductor layer 1303, and the firstelectrical connection part 1304, an insulator 1305 is formed between theconductivity via v and the respective layers 1302, 1303 and 1304. Theinsulator 1305 may be formed of any material if it has an electricalinsulation characteristic. Preferably, the insulator 806 is formed of amaterial absorbing low amounts of light. For example, the insulator 1305may be formed of silicon oxide, silicon nitride, or other insulatingmaterial, e.g., SiO₂, SiO_(x)N_(y), Si_(x)N_(y), etc.

In this embodiment, when the second electrical connection part 1307 isformed at a lower portion of the second-conductivity type semiconductorlayer 1301, it is unnecessary to separately form an electrode on the topsurface of the second-conductivity type semiconductor layer 1301.Accordingly, an amount of light emitted to the top surface of thesecond-conductivity type semiconductor layer 1301 may increase. In thiscase, since the conductive via v is formed at a portion of the activelayer 1302, the light emitting region is reduced. However, since noelectrode is formed on the top surface of the second-conductivity typesemiconductor layer 1301, the light extraction efficiency may be furtherimproved. Meanwhile, in the semiconductor light emitting device 1300according to this embodiment of the present invention, since noelectrode is disposed on the top surface of the second-conductivity typesemiconductor layer 1301, the entire electrode arrangement is moresimilar to a horizontal electrode structure rather than a verticalelectrode structure. However, the current dispersion effect may besufficiently ensured by the conductive via v formed in the inside of thesecond-conductivity type semiconductor layer 1301. In addition, theuneven structure may be formed on the top surface of thesecond-conductivity type semiconductor layer 1301. Such a structure mayincrease the probability that light incident from the active layer 1302will be emitted to the outside.

As described above, the semiconductor light emitting device may bedriven at an AC voltage. To this end, as illustrated in FIG. 77, thefirst light emitting structure C1 and the second light emittingstructure C2 form an n-p junction. For example, the n-p junction may beimplemented by connecting the second electrical connection part v of thefirst light emitting structure C1 to the first electrical connectionpart 1304 of the second light emitting structure C2, and applying anexternal voltage to the first electrical connection part 1304 of thefirst light emitting structure C1 and the second electrical connectionpart 1307 of the second light emitting structure C2. Specifically, inFIG. 77A, terminals A and B correspond to the first electricalconnection part 1304 of the first light emitting structure C1 and thesecond electrical connection part 1307 of the second light emittingstructure C2, respectively. A terminal C corresponds to the substrate1306. In this case, as illustrated in FIG. 77B, an AC light emittingdevice may be implemented by connecting the terminals A and B andapplying an AC signal to the connection node of the terminals A and Band the terminal C.

FIGS. 78 through 80 are schematic cross-sectional views illustrating amodified embodiment of the semiconductor light emitting device of FIG.76. The modified embodiment of FIGS. 78 through 80 is different from theforegoing embodiments in the electrical connection structure between thelight emitting structures, but its circuit diagram is identical to FIG.77. In the semiconductor light emitting device 1400 of FIG. 78, firstand second light emitting structures C1 and C2 are disposed on asubstrate 1406. The first light emitting structure C1 has the samestructure as the first light emitting structure of FIG. 76. Unlike theforegoing embodiment, a vertical electrode structure may be employed ata portion of the light emitting structure. In this embodiment, thesecond light emitting structure C2 has a vertical electrode structure.Specifically, the first-conductivity type semiconductor layer 1403, theactive layer 1402, and the second-conductivity type semiconductor layer1401 are sequentially formed on the first electrical connection part1404 connected to the substrate 1406, and the second electricalconnection part 1407 is formed on the second-connectivity typesemiconductor layer 1401.

FIGS. 79 and 80 illustrate a structure in which the substrates in FIGS.76 and 78 are formed of a material having an electrical insulationcharacteristic. The semiconductor light emitting device 1500 of FIG. 79includes first and second light emitting structures C1 and C2 on asubstrate 1506 having an electrical insulation characteristic. In thiscase, like the embodiment of FIG. 76, each of the first and second lightemitting structures C1 and C2 includes a first-conductivity typesemiconductor layer 1503, an active layer 1502, and asecond-conductivity type semiconductor layer 1501, which are stacked onthe first electrical connection part 1504. The second electricalconnection parts 1507 a and 1507 b have conductive vias v connected tothe second-conductivity type semiconductor layers 1501. Also, aninsulator 1505 is formed in order to electrically separate the secondelectrical connection parts 1507 a and 1507 b from the first electricalconnection part 1504, the first-conductivity type semiconductor layer1503, and the active layer 1502. With the use of the electricallyinsulating substrate 1506, the second electrical connection part 1507 aof the first light emitting structure C1 is connected to the firstelectrical connection part 1504 of the second light emitting structureC2 by a region which extends from the conductive via v in a directionparallel to the substrate 1506.

Like the embodiment of FIG. 78, in the case of the semiconductor lightemitting device 1600 of FIG. 80, a second light emitting structure C2includes a first-conductivity type semiconductor layer 1603, an activelayer 1602, and a second-conductivity type semiconductor layer 1601which are sequentially formed on a first electrical connection part1604. A second electrical connection part 1607 is formed on thesecond-conductivity type semiconductor layer 1601. With the use of theelectrically insulating substrate 1606, a second electrical connectionpart 1607 a of the first light emitting structure C1 extends from theconductive via v, which is connected to the second-conductivity typesemiconductor layer 1601, to the second light emitting structure C2 in adirection parallel to the substrate 1606. Accordingly, the first andsecond light emitting structures C1 and C2 may share the secondelectrical connection part 1607 a.

Meanwhile, although the AC-driving light emitting device is implementedwith two light emitting structures in the above-described embodiments,various modifications may be made in the number and connection structureof the light emitting structure, i.e., the light emitting diode (LED).FIG. 81 is a circuit diagram of the semiconductor light emitting deviceaccording to this embodiment of the present invention. In FIG. 81, eachdiode corresponds to an LED, i.e., the light emitting structure. Thecircuit diagram of FIG. 81 corresponds to a so-called ladder networkcircuit which has fourteen light emitting structures. In this case, whena forward voltage is applied, nine light emitting structures areoperated. Even when a reverse voltage is applied, nine light emittingstructures are operated. To this end, as illustrated in FIG. 81, thereare three basic electrical connection structures, i.e., an n-p junction,an n-n junction, and a p-p junction. Examples of the n-p junction, then-n junction, and the p-p junction will be described below. Using thosebasic junctions, it is possible to obtain an AC driving light emittingdevice having a various number of LEDs and various circuitconfigurations.

FIGS. 82 and 83 are schematic cross-sectional views illustrating theimplementation example of the n-p junction. Referring to FIGS. 82 and83, first and second light emitting structures C1 and C2 which form then-p junction are disposed on substrates 1706 and 1706′. Each of thefirst and second light emitting structures C1 and C2 includes afirst-conductivity type semiconductor layer 1703, an active layer 1702,and a second-conductivity type semiconductor layer 1701 which aresequentially stacked on a first electrical connection part 1704. Aconductive via v is connected to the inside of the second-conductivitytype semiconductor layer 1701, and an insulator 1705 is formed forseparately separating the conductive via v from a first electricalconnection part 1704, the first-conductivity type semiconductor layer1703, and the active layer 1702. A second electrical connection part1707 of the first light emitting structure C1 is connected to the firstelectrical connection part 1704 of the second light emitting structureC2. In this case, the structure of FIG. 82 using the conductivesubstrate 1706 and the structure of FIG. 83 using the electricallyinsulating substrate 1706′ are different in the form of the secondelectrical connection part 1707, and are similar to those of FIGS. 76and 97, respectively. Since the case of the n-p junction constitutes theentire device by connection to other light emitting structures, ratherthan having its sole use in AC driving, it can be understood that thesecond electrical connection part provided in the second light emittingstructure C2, i.e., the conductive via v, is not the structure forapplying an external electric signal but it is in such a state that itis electrically connected to other light emitting structure.

FIGS. 84 through 86 are schematic cross-sectional views illustrating theimplementation example of the n-n junction. Referring to FIGS. 84through 86, first and second light emitting structures C1 and C2 whichform the n-n junction are disposed on substrates 1806 and 1806′. Each ofthe first and second light emitting structures C1 and C2 includes afirst-conductivity type semiconductor layer 1803, an active layer 1802,and a second-conductivity type semiconductor layer 1801 which aresequentially stacked on a first electrical connection part 1804. Aconductive via v is connected to the inside of the second-conductivitytype semiconductor layer 1801, and an insulator 1805 is formed forseparately separating the conductive via v from a first electricalconnection part 1804, the first-conductivity type semiconductor layer1803, and the active layer 1802. In order to form the n-n junction, itis necessary to connect second electrical connection parts 1807 of thefirst and second light emitting structures C1 and C2. As one example, asillustrated in FIG. 84, conductive vias v provided in the first andsecond light emitting structures C1 and C2 may be connected togetherthrough the conductive substrate 1806. In addition, as illustrated inFIG. 85, in a case in which an electrically insulating substrate 1806′is used, the second electrical connection part 1807 may connect theconductive vias v provided in the first and second light emittingstructures C1 and C2 by a region which extends in a direction parallelto the substrate 1806′. In addition to the connection method using theelectrical connection part, the second-conductivity type semiconductorlayer 1801′ may be used as illustrated in FIG. 86. The first and secondlight emitting structures C1 and C2 may share the second-conductivitytype semiconductor layer 1801′. In this case, the n-n junction may beimplemented without separately connecting the conductive vias providedin the first and second light emitting structures C1 and C2.

FIGS. 87 through 89 are schematic cross-sectional views illustrating theimplementation example of the p-p junction. Referring to FIGS. 87through 89, first and second light emitting structures C1 and C2 whichform the p-p junction are disposed on substrates 1806 and 1806′. Each ofthe first and second light emitting structures C1 and C2 includes afirst-conductivity type semiconductor layer 1903, an active layer 1902,and a second-conductivity type semiconductor layer 1901 which aresequentially stacked on a first electrical connection part 1904. Aconductive via v is connected to the inside of the second-conductivitytype semiconductor layer 1901, and an insulator 1905 is formed forseparately separating the conductive via v from a first electricalconnection part 1904, the first-conductivity type semiconductor layer1903, and the active layer 1902. In order to form the p-p junction, itis necessary to connect first electrical connection parts 1904 of thefirst and second light emitting structures C1 and C2. In this case,conductive vias v may be connected to other light emitting structures(not shown) constituting the entire AC light emitting device. As oneexample of the p-p junction, as illustrated in FIG. 87, the firstelectrical connection parts 1904 provided in the first and second lightemitting structures C1 and C2 may be connected together through theconductive substrate 1906. In addition, as illustrated in FIG. 89, in acase in which an electrically insulating substrate 1906′ is used, thefirst electrical connection parts 1904 may be connected together througha separate metallic connection layer 1908. Furthermore, as illustratedin FIG. 89, a structure which commonly uses the first electricalconnection parts 1904, instead of providing the separate connectionmetal layer, may be employed for the first and second light emittingstructures C1 and C2.

A semiconductor light emitting device according to another embodiment ofthe present invention will be described below with reference to FIGS. 90through 100.

FIG. 90 is a cross-sectional view of a vertical type semiconductor lightemitting device according to this embodiment of the present invention,and FIGS. 91 and 92 are cross-sectional views illustrating modifiedembodiments of the vertical type semiconductor light emitting structuresof FIG. 90.

Referring to FIG. 90, the vertical type semiconductor light emittingdevice 2000 according to this embodiment of the present inventionincludes a light emitting structure which is constituted by an n-typesemiconductor layer 2001, a p-type semiconductor layer 2003, and anactive layer 2002 formed between the n-type semiconductor layer 2001 andthe p-type semiconductor layer 2003. A reflective metal layer 2004 and aconductive substrate 2005 are formed under the light emitting structure.In addition, an n-type electrode 2006 is formed on the n-typesemiconductor layer 2001, and a passivation layer 2007 having an unevenstructure is formed to cover the side surface of the light emittingstructure.

The n-type semiconductor layer 2001 and the p-type semiconductor layer2003 may be formed of nitride semiconductors. That is, the n-typesemiconductor layer 2001 and the p-type semiconductor layer 2003 may beformed of semiconductor materials into which n-type impurity and p-typeimpurity are doped, which have a composition ofAl_(x)In_(y)Ga_((1-x-y))N (where 0≦x≦1, 0≦y≦1, 0≦x+y≦1), e.g., GaN,AlGaN, InGaN, etc. Examples of the n-type impurity include Si, Ge, Se,Te, and so on, and examples of the p-type impurity include Mg, Zn, Be,and so on. Meanwhile, in order to improve the efficiency of lightemitted in a vertical direction, an uneven structure may be formed onthe top surface of the n-type semiconductor layer 101.

The active layer 2002 formed between the n-type nitride semiconductorlayer 2001 and the p-type nitride semiconductor layer 2003 emits lighthaving a predetermined energy due to electron/hole recombination and mayhave a multiple quantum well (MQW) structure in which a quantum welllayer and a quantum barrier layer are alternately stacked. For example,an InGaN/GaN structure may be used for the multiple quantum wellstructure.

The reflective metal layer 2004 may reflect light emitted from theactive layer 2002 toward the n-type nitride semiconductor layer 2001 andmay be formed of Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, or Au. In thiscase, although not illustrated in detail, the reflective metal layer2004 may have a structure capable of improving the reflectionefficiency. Specifically, the reflective metal layer 2004 may includeany one of Ag, Al, Ni/Ag, Zn/Ag, Ni/Al, Zn/Al, Pd/Ag, Pd/Al, Ir/Ag,Ir/Au, Pt/Ag, Pt/Al, Ni/Ag/Pt, and combinations thereof. In thisembodiment, the reflective metal layer 2004 is not a requisite element.In some cases, the reflective metal layer 2004 may be omitted.

The conductive substrate 2005 functions as a p-type electrode andfunctions as a support body which supports the light emitting structure,i.e., the n-type semiconductor layer 2001, the active layer 2002, andthe p-type semiconductor layer 2003, in a laser lift-off process, whichwill be described later. In this case, the conductive structure 2005 mayinclude at least one material selected from the group consisting of Si,Cu, Ni, Au, W, and Ti. The conductive substrate 2005 may be formed usinga plating method, a deposition method, or a bonding method, depending onthe selected material.

The passivation layer 2007 is an insulation layer for protecting thelight emitting structure, in particular, the active layer 2002. Thepassivation layer 2007 is formed in the region where a portion of thelight emitting structure is removed. Specifically, as illustrated inFIG. 90, the passivation layer 2007 may extend to a portion of the topsurface of the n-type semiconductor layer 2001 and the top surface ofthe reflective metal layer 2004, as well as the side surface of thelight emitting structure. In a case in which the reflective metal layer2004 is not employed, the passivation layer 2007 is formed on the topsurface of the conductive substrate 2005. In a case in which a portionof the light emitting structure is removed and exposed, as illustratedin FIG. 90, the exposed side may be inclined upward. Such a structuremay lead to the improvement in the light emitting area. Furthermore, thepassivation layer 2007 may be formed more easily.

In order to perform the protection function, the passivation layer 2007may be formed of silicon oxide or silicon nitride, e.g., SiO₂,SiO_(x)N_(y), Si_(x)N_(y), etc., and may have a thickness ofapproximately 0.01-2 μm. Accordingly, the passivation layer 2007 mayhave a refractive index of approximately 1.4-2.0. Due to air or packagemold structure and refractive index difference, it may be difficult forlight emitted from the active layer 2002 to be emitted to the outside.In particular, in the case of the vertical type semiconductor lightemitting device 2000 according to this embodiment of the presentinvention, since the p-type semiconductor layer 2003 is relatively thin,light emitted in a lateral direction of the active layer 2002 may passthrough the passivation layer 2007 and be emitted to the outside.However, it is difficult for light emitted from the active layer 2002toward the passivation layer 2007 in a lateral direction to be emittedto the outside because an incident angle with respect to the outersurface of the passivation layer 2007 is very small.

In this embodiment, the external light extraction efficiency is improvedby forming the uneven structure in the passivation layer 2007. Inparticular, as illustrated in FIG. 90, when the uneven structure isformed in a region through which light emitted in a lateral direction ofthe active layer 2002 passes, the amount of light emitted to the sidesurface of the vertical type semiconductor light emitting device 2000may increase. The region through which the light emitted in the lateraldirection of the active layer 2002 may be considered as a portion of thetop surface of the reflective metal layer 2004 where the light emittingstructure is not formed. Specifically, when comparing the case in whichthe uneven structure is employed in the passivation layer 2007 with thecase in which no uneven structure is employed therein, in a state whereall elements other than the uneven structure are identical, the lightextraction efficiency was improved by more than approximately 5%.Meanwhile, although not necessarily required, the uneven structure ofthe passivation layer 2007 may be formed in a region corresponding tothe top surface of the n-type semiconductor layer 2001. In this case,the light extraction efficiency in a vertical direction may be improved.

As illustrated in FIGS. 91 and 92, the uneven structure formation regionof the passivation layer may be modified in various manners in order tomaximize the external light extraction efficiency. Referring to FIG. 91,the uneven structure may be formed up to the side surface of thepassivation layer 2007′. Also, referring to FIG. 92, the unevenstructure may also be formed on the bottom surface of the passivationlayer 2007″, i.e., the surface directing the reflective metal layer2004. In this case, a pattern having a corresponding shape may be formedon the reflective metal layer 2004.

FIGS. 93 through 96 are cross-sectional views illustrating a method ofmanufacturing the vertical type semiconductor light emitting devicedescribed above with reference to FIG. 90.

Referring to FIG. 93, a light emitting structure is formed on asubstrate 2008 for semiconductor single-crystal growth by sequentiallygrowing an n-type semiconductor layer 2001, an active layer 2002, and ap-type semiconductor layer 2003 through a semiconductor layer growthprocess, e.g., MOCVD, MBE, HVPE, etc. The substrate B may be formed ofsapphire, SiC, MgAl₂O₄, MaO, LiAlO₂, LiGaO₂, or GaN. Sapphire is acrystal having a Hexa-Rhombo R3c symmetry, and has a lattice constant of13,001 Å along a c-axis and a lattice constant of 4,758 Å along ana-axis. Sapphire has a C(0001) plane, an A(1120) plane, and an R(1102)plane. In this case, the C plane is mainly used as a nitride growthsubstrate because it facilitates the growth of a nitride thin film andis stable at high temperatures.

Referring to FIG. 94, a reflective metal layer 2004 and a conductivesubstrate 2005 are formed on the p-type semiconductor layer 2003 througha plating process or a submount bonding process. Although notillustrated in detail, the substrate 2008 is removed by an appropriatelift-off process, e.g., a laser lift-off process or a chemical lift-offprocess.

Referring to FIG. 95, a portion of the light emitting structure isremoved for device-based dicing and the formation of a passivationlayer. In this case, the side surface exposed by the removal may beinclined upward. Also, in order to improve the light extractionefficiency in a vertical direction, an uneven structure may be formed bya wet etching process on the top surface of the n-type semiconductorlayer 2001, i.e., the surface exposed by the removal of the substrate2008 for a semiconductor single-crystal growth.

Referring to FIG. 96, a passivation layer 2007 is formed for protectingthe light emitting structure. At this step, for example, the passivationlayer 2007 may be formed by appropriately depositing silicon oxide orsilicon nitride. The lateral light emission efficiency may be improvedby forming the uneven structure on a light emission surface of thepassivation layer 2007. In this case, the uneven structure may be formedby using a dry etching process or a wet etching process which is knownto those skilled in the art. Also, if necessary, the uneven structuremay be formed on another light emission surface of the passivation layer2007. After forming the passivation layer 2007, the structure of FIG. 92may be obtained by forming an n-type electrode on the top surface of then-type semiconductor layer 2001.

This embodiment of the present invention provides a modified verticaltype semiconductor light emitting device in order to further improveelectrical characteristics and optical characteristics.

FIG. 97 is a schematic cross-sectional view of a semiconductor lightemitting device according to another embodiment of the presentinvention. Referring to FIG. 97, the semiconductor light emitting device2210 includes a conductive substrate 2105, a light emitting structure, asecond-conductivity type electrode 2106, and a passivation layer 2107.The light emitting structure a first-conductivity type semiconductorlayer 2103, an active layer 2102, and a second-conductivity typesemiconductor layer 2101, which are sequentially formed on theconductive substrate 2105. The second-conductivity type electrode 2106applies an electric signal to the second-conductivity type semiconductorlayer 2101. The passivation layer 2107 has an uneven structure on theside surface of the light emitting structure. Compared with thestructures of FIG. 90 and so on, the active layer 2102 in FIG. 97 isdisposed at a relatively upper portion, but the position of the activelayer 2102 may be changed in various manners. For example, the activelayer 2102 may be formed at a similar height to the bottom surface ofthe passivation layer 2107.

Unlike the foregoing embodiments in which the n-type electrode is formedon the exposed surface of the n-type semiconductor layer where thesapphire substrate is removed, the n-type electrode is exposed to theoutside in a direction of the lower portion of the n-type semiconductorlayer by using a conductive via. Specifically, the second-conductivitytype electrode 2106 includes a conductive via v and an electricalconnection part P. The conductive via v passes through thefirst-conductivity type semiconductor layer 2104 and the active layer2102 and is connected to the second-conductivity type semiconductorlayer 2101 at the inside thereof. The electrical connection part Pextends from the conductive via v and is exposed to the outside of thelight emitting structure. In this case, since the second-conductivitytype electrode 2106 needs to be electrically separated from thefirst-conductivity type semiconductor layer 2103 and the active layer2102, an insulator 2108 is formed appropriately around thesecond-conductivity type electrode 2106. The insulator 2108 may beformed of any material if it has a low electrical conductivity.Preferably, a material having a low light absorption is used for theinsulator 2108. For example, the insulator 2108 may be formed of thesame material as the passivation layer 2107.

The second-conductivity type electrode 2106 may be formed of a metallicmaterial which forms an ohmic contact with the second-conductivity typesemiconductor layer 2101. Also, the entire second-conductivity typeelectrode 2106 may be formed of the same material. However, since theelectrical connection part P may be used as a bonding pad part, theelectrical connection part may be formed of a material different fromother parts. Meanwhile, considering the above-described manufacturingprocess, the first-conductivity type semiconductor layer 2101 and thesecond-conductivity type semiconductor layer 2103 may be, but are notlimited to, a p-type semiconductor layer and an n-type semiconductorlayer, respectively. As illustrated in FIG. 97, a first contact layer2104 may be further formed between the first-conductivity typesemiconductor layer 2103 and the conductive substrate 2105. The firstcontact layer 2104 may be formed of a high reflectivity metal, such asAg or Al. In this case, the first contact layer 2104 and thesecond-conductivity type electrode 2106 are electrically separated bythe insulator 2108.

Due to such an electrical connection structure, an electric signal maybe applied not from the top surface but rather from the inside of thesecond-conductivity type semiconductor layer 2101. In particular, sinceno electrode is formed on the top surface of the second-conductivitytype semiconductor layer 2101, the light emitting area may increase, andthe current dispersion effect may be improved by the conductive via vformed inside the second-conductivity type semiconductor layer 2101. Inthis case, the desired electrical characteristic may be obtained byappropriately adjusting the number, area and shape of the conductive viav. In this embodiment, the main processes, e.g., a process of formingthe conductive substrate or a process of removing the sapphiresubstrate, use processes commonly used in manufacturing a vertical typesemiconductor light emitting device. However, the structure obtained bythe processes may be considered to be closer to a horizontal structure.Thus, the semiconductor light emitting device according to thisembodiment of the present invention may be referred to as avertical/horizontal type structure in which the vertical structure andthe horizontal structure are combined.

Like the foregoing embodiments, the passivation layer 2107 is formed onthe side surface of the light emitting structure, and the unevenstructure is formed on the path of light emitted from the active layer2102, thereby improving the extraction efficiency of light emitted fromthe active layer 2102 toward the passivation layer 2107 in the lateraldirection. In addition, as illustrated in FIG. 97, the uneven structuremay also be formed on the top surface of the second-conductivity typesemiconductor layer 2101. Although not illustrated, the uneven structuremay also be formed on the inclined side surface of the passivation layer2107.

FIG. 98 is a schematic cross-sectional view illustrating a modifiedembodiment of the semiconductor light emitting device of FIG. 97. Theembodiment of FIG. 98 has a structure in which an etch stop layer 2109is further included in the structure of FIG. 97. Hence, the etch stoplayer 2109 only will be described below. The etch stop layer 2109 isformed in a region of the top surface of at least the conductivesubstrate 2105 where the light emitting structure is not formed. Theetch stop layer 2109 is formed of a material (e.g., oxide such as SiO₂)having a different etching characteristic from a semiconductor material(nitride semiconductor) constituting the light emitting structure withrespect to a specific etching process. Since it may be possible to etchup to the region where the etch stop layer 2109 is disposed during theetching of the light emitting structure, the etching depth can becontrolled by the etch stop layer 2109. In this case, the etch stoplayer 2109 and the insulator 2108 may be formed of the same material inorder for the facilitation of the etching process. When the lightemitting structure is etched because it is necessary to expose thesecond-conductivity type electrode 2106 to the outside, the materialconstituting the conductive substrate 2105 or the first contact layer2104 is deposited on the side surface of the light emitting structure,causing the occurrence of a leakage current. Such a problem may beminimized by previously forming the etch stop layer 2109 under the lightemitting structure which will be etched and removed.

FIG. 99 is a schematic cross-sectional view of a semiconductor lightemitting device according to another embodiment of the presentinvention. FIG. 100 illustrates a structure in which an etch stop layeris further included in the structure of FIG. 99. Referring to FIG. 99,the semiconductor light emitting device 2200 includes a conductivesubstrate 2205, a light emitting structure, a second contact layer 2204,a conductive via v, and a passivation layer 2207. The light emittingstructure includes a first-conductivity type semiconductor layer 2203,an active layer 2202, and a second-conductivity type semiconductor layer2201 which are sequentially formed on the conductive substrate 2205. Thesecond contact layer 2204 applies an electric signal to thesecond-conductivity type semiconductor layer 2201. The conductive via vextends from the conductive substrate 2205 up to the inside of thesecond-conductivity type semiconductor layer 2201. The passivation layer2207 has an uneven structure on the side surface of the light emittingstructure.

Unlike the structure of FIG. 97, the conductive substrate 2205 iselectrically connected to the second-conductivity type semiconductorlayer 2201, and the first contact layer 2204 connected to thefirst-conductivity type semiconductor layer 2203 has an electricalconnection part P and is exposed to the outside. The conductivesubstrate 2205 may be electrically separated from the first contactlayer 2204, the first-conductivity type semiconductor layer 2203, andthe active layer 2202 by the insulator 2208. That is, unlike theembodiment of FIG. 97 in which the second-conductivity type electrode2106 connected to the second-conductivity type semiconductor layer 2101is exposed to the outside to thereby provide the electrical connectionpart P, the first contact layer 2204 connected to the first-conductivitytype semiconductor layer 2203 is exposed to the outside to therebyprovide the electrical connection part P. The effects obtained from thestructures, except for the electrical connection method, are identicalto those of FIG. 97. As illustrated in FIG. 100, an etch stop layer 2209may be adopted. Compared with the embodiment of FIG. 97, the embodimentof FIG. 99 in which the first contact layer 2204 is exposed to theoutside is easier in the process of forming the insulator 2208.

A semiconductor light emitting device according to another embodiment ofthe present invention will be described below with reference to FIGS.101 through 119.

Referring to FIG. 101, the semiconductor light emitting device 2300according to this embodiment of the present invention may have thefollowing semiconductor stack structure. A substrate formed of an Si—Alalloy (hereinafter, referred to as an Si—Al alloy substrate) 2301, apassivation layer 2320 formed on the top and bottom surfaces of theSi—Al alloy substrate 2301, a bonding metal layer 2302, a reflectivemetal layer 2303, a p-type semiconductor layer 2304, an active layer2305, and an n-type semiconductor layer 2306 are stacked in sequence.The p-type semiconductor layer 2304, the n-type semiconductor layer2306, and the active layer 2305 may be formed of GaN-basedsemiconductor, e.g., Al_(x)Ga_(y)In_((1-x-y))N (where, 0≦x≦1, 0≦y≦1,0≦x+y≦1) and form the light emitting structure.

An n-type electrode 2307 is formed on the n-type semiconductor layer2306. The reflective metal layer 2303 disposed between the bonding metallayer 2302 and the p-type semiconductor layer 2304 reflects lightincident from the semiconductor layer in an upward direction, therebyfurther increasing the brightness of the semiconductor light emittingdevice. The reflective metal layer 2303 may be formed of a highreflectivity metal, e.g., Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au,Ni/Ag, Zn/Ag, Ni/Al, Zn/Al, Pd/Ag, Pd/Al, Ir/Ag, Ir/Au, Pt/Ag, Pt/Al,and Ni/Ag/Pt, or at least one material including the high reflectivitymetal. However, in some cases, the reflective metal layer 2303 may notbe formed. The bonding metal layer 2302 functions to bond the Si—Alalloy substrate 2301 with the light emitting structure, and a conductiveadhesive may be used therein.

Examples of the conductive adhesive include Au, Sn, Ni, Au—Sn, Ni—Sn,Ni—Au—Sn, and Pb—Sr. In this embodiment, although the semiconductorlight emitting device 2300 includes the bonding metal layer 2302, theSi—Al alloy substrate 2301 may be directly bonded on the p-typesemiconductor layer 2304, without the bonding metal layer 2302.Accordingly, the semiconductor light emitting device 2300 uses aconductive substrate as the Si—Al alloy substrate 2301.

The Si—Al alloy is advantageous in view of its thermal expansioncoefficient, heat conductivity, mechanical process, and price. That is,the thermal expansion coefficient of the Si—Al alloy substrate 2301 issimilar to that of the sapphire substrate. Thus, the use of Si—Al alloysubstrate 2301 in the manufacture of the semiconductor light emittingdevice 2300 reduces warpage of the substrate and crack in the lightemitting structure, which have previously occurred in the process ofbonding the existing Si conductive substrate and the process ofseparating the sapphire substrate by the laser irradiation.Consequently, the high-quality low-defect semiconductor light emittingdevice 2300 may be obtained.

Also, the Si—Al alloy substrate 2301 has an excellent heat dissipationcharacteristic because its heat conductivity is in the range ofapproximately 120-180 W/m·k. Furthermore, since the Si—Al alloysubstrate 2301 can be easily manufactured by melting Si and Al at a highpressure, it can be easily obtained at low cost.

In particular, the semiconductor light emitting device 2300 according tothis embodiment of the present invention further includes thepassivation layer 2320 on the top and bottom surfaces of the Si—Al alloysubstrate 2301. The passivation layer 2320 prevents the penetration ofchemicals into the Si—Al alloy substrate 2301 during a cleaning process.The passivation layer 2320 may be formed of a metal or a conductivedielectric. When the passivation layer 2320 is formed of a metal, it mayinclude any one of Ni, Au, Cu, W, Cr, Mo, Pt, Ru, Rh, Ti, Ta, and alloysthereof. In this case, the passivation layer 2320 may be formed using anelectroless plating process, a metal deposition process, a sputterprocess, or a CVD process. A seed metal layer 2310 acting as a seedduring the process of plating the passivation layer 2320 may be furtherformed between the Si—Al alloy substrate 2301 and the metal passivationlayer 2320. The seed metal layer 2310 may be formed of Ti/Au.Furthermore, the passivation layer 2320 may be formed of a conductivedielectric, e.g., indium tin oxide (ITO), indium zinc oxide (IZO), orcopper indium oxide (CIO). In this case, the passivation layer 2320 maybe formed using a deposition process or a sputter process. Thepassivation layer 2320 may be formed in the thickness range ofapproximately 0.01-20 μm. Preferably, the passivation layer 2320 isformed in the thickness range of approximately 1-10 μm.

A method of manufacturing a semiconductor light emitting deviceaccording to an embodiment of the present invention will be describedbelow with reference to FIGS. 102 through 109. FIGS. 102 through 109 arecross-sectional views illustrating a method of manufacturing asemiconductor light emitting device according to an embodiment of thepresent invention.

As illustrated in FIG. 102, a sapphire substrate 2350 is prepared as agrowth substrate. As illustrated in FIG. 103, an n-type semiconductorlayer 2306, an active layer 2305, and a p-type semiconductor layer 2304are sequentially formed on the sapphire substrate 2350. As illustratedin FIG. 104, a reflective metal layer 2303 is formed on the p-typesemiconductor layer 2304. The reflective metal layer 2303 is formed of ahigh reflectivity metal, e.g., Au, Al, Ag, or Ru. In some cases, thereflective metal layer 2303 may not be formed. As illustrated in FIG.105, a passivation layer 2320 is formed on the surface of the Si—Alalloy substrate 2301. The passivation layer 2302 may be formed using ametal or a conductive dielectric.

When the passivation layer 2320 is formed of a metal, it may include anyone of Ni, Au, Cu, W, Cr, Mo, Pt, Ru, Rh, Ti, Ta, and alloys thereof. Inthis case, the passivation layer 2320 may be formed using an electrolessplating process, a metal deposition process, a sputter process, or a CVDprocess. When the metal passivation layer 2320 is formed using theelectroless plating process, a seed metal layer 2310 acting as a seedduring the process of plating the passivation layer 2320 may be furtherformed before the forming of the passivation layer 2320 on the surfaceof the Si—Al alloy substrate 2301.

When the passivation layer 2320 is formed of a conductive dielectric, itmay be formed of ITO, IZO, or CIO. In this case, the passivation layer2320 may be formed using a deposition process or a sputter process. Thepassivation layer 2320 may be formed in the thickness range ofapproximately 0.01-20 μm. Preferably, the passivation layer 2320 isformed in the thickness range of approximately 1-10 μm. If the thicknessof the passivation layer 2320 is less than 0.01 μm, the passivationlayer 2320 may not prevent the penetration of chemicals, e.g., HCl, HF,KOH, etc., which will be described later. If the thickness of thepassivation layer 2320 is greater than 20 μm, the thermal expansioncoefficient of the Si—Al alloy substrate 2301 may be changed. Thus, thepassivation layer 2320 is formed to the above thickness range.

Although not illustrated, after forming the passivation layer 2320, thesurface roughness may be improved by performing a chemical mechanicalpolishing (CMP) process on the surface of the passivation layer 2320.

As illustrated in FIG. 106, the Si—Al alloy substrate 2301 where thepassivation layer 2320 is formed on the surface thereof is bonded to thereflective metal layer 2303 by using the bonding metal layer 2302.Although the Si—Al alloy substrate 2301 may be bonded using the bondingmetal layer 2302, the Si—Al alloy substrate 2301 where the passivationlayer 2320 is formed on the surface thereof may be directly bonded onthe reflective metal layer 2303.

As illustrated in FIG. 107, the sapphire substrate 2350 is separatedfrom the n-type semiconductor layer 2306 by a laser lift-off (LLO)process. After separating the sapphire substrate 2350, a cleaningprocess may be performed using chemicals such as HCl, HF, or KOH.

As illustrated in FIG. 108, a plurality of n-type electrodes 2307 areformed on the n-type semiconductor layer 2306 exposed by the separationof the sapphire substrate 2350. Before forming the n-type electrodes2307, a texturing process using HOH or the like may be performed on thesurface of the n-type semiconductor layer 2306 in order to improve thelight extraction efficiency of the semiconductor light emitting device.

As illustrated in FIG. 109, the n-type semiconductor layer 2306, theactive layer 2305, the p-type semiconductor layer 2304, the reflectivemetal layer 2303, the bonding metal layer 2302, the passivation layer2320, the seed metal layer 2310, and the Si—Al alloy substrate 2301between the n-type electrodes 2307 are diced into chips. Consequently,the semiconductor light emitting device 2300 may be obtained.

In the semiconductor light emitting device according to this embodimentof the present invention, the formation of the passivation layer 2320,such as Ni, on the surface of the Si—Al alloy substrate 2301 may preventthe aluminum (Al) of the Si—Al alloy substrate 2301 from being etched bychemicals such as HCl, HF or KOH used in the cleaning process, after theseparation of the sapphire substrate 2350, or KOH used in the texturingprocess on the surface of the n-type semiconductor layer 2306.

Accordingly, the semiconductor light emitting device according to thisembodiment of the present invention may prevent the formation of unevenpatterns on the surface of the Si—Al alloy substrate 2301. Consequently,it may be possible to prevent the peeling of the light emittingstructure attached on the Si—Al alloy substrate 2301.

When a metal such as Ni is used for the passivation layer 2320, thesurface roughness of the Si—Al alloy substrate 2301 is improved, so thatthe Si—Al alloy substrate 2301 and the light emitting structure arefirmly attached. In the conventional art, before forming the bondingmetal layer 2302, the cleaning process using chemicals such as acid isperformed for removing a natural oxide layer, and the surface unevenpattern of approximately 200-500 nm is formed while aluminum (Al) on thesurface of the Si—Al alloy substrate 2301 is etched. However, accordingto this embodiment of the present invention, if the Ni CMP process isperformed after forming the passivation layer 2320 of a metal such as Nion the surface of the Si—Al alloy substrate 2301, the uneven pattern isreduced to less than 5 nm, thereby improving the surface roughness likea mirror plane.

As illustrated in FIG. 110, a semiconductor light emitting device 2300′as a modified embodiment is substantially identical to the foregoingembodiment. However, the passivation layer 2320 is not formed on theentire top and bottom surfaces of the Si—Al alloy substrate 2301.Specifically, the passivation layer 2320 is formed on the top surface ofthe Si—Al alloy substrate 2301 so that a portion of the Si—Al alloysubstrate 2301 is exposed. A conductive layer 2322 is further formed onthe passivation layer 2320 and the top surface of the Si—Al alloysubstrate 2301 which is exposed by the passivation layer 2320. A contactmetal layer 2323 is formed on the bottom surface of the Si—Al alloysubstrate 2301. In particular, the passivation layer 2320 may be formedof an insulating material, instead of a metal or a conductivedielectric. That is, in the semiconductor light emitting deviceaccording to the modified embodiment of the present invention, thepassivation layer 2320 is formed of an insulating material, instead of ametal or a conductive dielectric, and the passivation layer 2320 isformed to expose a portion of the top surface of the Si—Al alloysubstrate 2301 in order to electrify the Si—Al alloy substrate 2301,where the passivation layer 2320 is formed, and the light emitting alloysubstrate 2301, where the passivation layer 2320 is formed, and thelight emitting structure formed on the passivation layer 2320. Also, theconductive layer 2322 is further formed on the passivation layer 2320and the Si—Al alloy substrate 2301. The conductive layer 2322 may beformed of a metal.

Hereinafter, a method of manufacturing a compound semiconductor lightemitting device according to a modified embodiment of the presentinvention will be described in detail. The description of the same partsas the foregoing embodiment will be omitted, and the different contentsonly will be described below.

Referring to FIGS. 102 through 104, an n-type semiconductor layer 2306,an active layer 2305, a p-type semiconductor layer 2304, and areflective metal layer 2303 are sequentially formed on a sapphiresubstrate 2350. In some cases, the reflective metal layer 2303 may notbe formed.

Referring to FIG. 111, a passivation layer 2320 is formed over an Si—Alalloy substrate 2301. The passivation layer 2320 may be formed of aninsulating material. The insulating passivation layer 2320 may be formedto a thickness of approximately 0.01-1 μm by using a CVD process or acoating process. Although not illustrated, after forming the passivationlayer 2320, a CMP process may be performed on the surface of thepassivation layer 2320.

Referring to FIG. 112, a portion of the passivation layer 2320 isremoved by an etching process to expose a portion of the top surface ofthe Si—Al alloy substrate 2301. Referring to FIG. 113, a conductivelayer 2322 is formed on the passivation layer 2320 and the Si—Al alloysubstrate 2301. Referring to FIG. 114, the conductive layer 2322 formedon the top surface of the Si—Al alloy substrate 2301 is attached on thereflective metal layer 2303 by using the bonding metal layer 2302.

Referring to FIG. 115, the sapphire substrate 2350 is separated from then-type semiconductor layer 2306 by a laser lift-off process. Afterseparating the sapphire substrate 2350, a cleaning process may beperformed using chemicals such as HCl, HF or KOH. Since the passivationlayer 2320 and the conductive layer 2322 are formed on the surface ofthe Si—Al alloy substrate 2301, it is possible to prevent aluminum (Al)of the Si—Al alloy substrate 2301 from being etched by the chemicalsused in the cleaning process.

Referring to FIG. 116, a plurality of n-type electrodes 2307 are formedon the n-type semiconductor layer 2306 exposed by the separation of thesapphire substrate 2350. Before forming the n-type electrodes 2307, atexturing process using HOH or the like may be performed on the surfaceof the n-type semiconductor layer 2306 in order to improve the lightextraction efficiency of the semiconductor light emitting device. Sincethe passivation layer 2320 and the conductive layer 2322 are formed onthe Si—Al alloy substrate 2301, it is possible to prevent the aluminum(Al) of the Si—Al alloy substrate 2301 from being etched by the chemicalused in the texturing process.

Referring to FIG. 117, a lapping process is performed to remove thebottom surface of the Si—Al alloy substrate 2301, including thepassivation layer 2320, by a predetermined thickness. Referring to FIG.118, a contact metal layer 2323 is formed on the bottom surface of theSi—Al alloy substrate 2301 exposed by the lapping process.

Referring to FIG. 119, the n-type semiconductor layer 2306, the activelayer 2305, the p-type semiconductor layer 2304, the reflective metallayer 2303, the bonding metal layer 2302, the conductive layer 2322, thepassivation layer 2320, the Si—Al alloy substrate 2301, and the contactmetal layer 2323 between the n-type electrodes 2307 are diced intochips. Consequently, the semiconductor light emitting device 2300′according to the modified embodiment of the present invention may beobtained.

<Light Emitting Device Package and Light Source Module>

A light emitting device package according to an embodiment of thepresent invention may include the above-described semiconductor lightemitting device.

The following description will be made with regard to light emittingdevice packages including the semiconductor light emitting devicesaccording to various embodiments of the present invention.

FIG. 120 is a schematic view of a white light emitting device packageaccording to an embodiment of the present invention.

Referring to FIG. 120, the white light emitting device package 3010according to this embodiment of the present invention includes a bluelight emitting device 3015 and a resin encapsulation part 3019 packagingthe blue light emitting device 3015 and having the top surface with aconvex lens shape.

As illustrated, the resin encapsulation part 3019 used in thisembodiment has a hemispherical lens shape in order to ensure a wideorientation. The blue light emitting device 3015 may be directlypackaged on a separate circuit board. The resin encapsulation part 3019may be formed of a silicon resin, an epoxy resin, or other transparentresins. A mixed material including a yellow phosphor, a green phosphor3012, a red phosphor 3014, a quantum dot (QD) phosphor, or at least onekind of the phosphors is dispersed or stacked in a layer structure inthe inside or outside of the resin encapsulation part 3019.

The green phosphor 3012 may be at least one phosphor selected from thegroup consisting of M₂SiO₄:Re silicate-based phosphor, MA₂D₄:Resulfide-based phosphor, β-SiAlON:Re phosphor, and MA′₂O₄:Re′ oxide-basedphosphor.

Herein, M is at least one element selected from Ba, Sr, Ca, and Mg, andA is at least one element selected from Ga, Al, and In. D is at leastone element selected from S, Se, and Te, and A′ is at least one elementselected from Sc, Y, Gd, La, Lu, Al, and In. Re is at least one elementselected from Eu, Y, La, Ce, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu,F, Cl, Br, and I. Re's is at least one element selected from Ce, Nd, Pm,Sm, Tb, Dy, Ho, Er, Tm, Yb, F, Cl, Br, and I.

Meanwhile, the red phosphor 3014 may be at least one selected fromMAlSiN_(x):Re nitride-based phosphor (1≦x≦5) and MD:Re sulfide-basedphosphor.

M is at least one selected from Ba, Sr, Ca, and Mg, and D is at leastone selected from S, Se, and Te. Re is at least one selected from Eu, Y,La, Ce, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, F, Cl, Br, and I.

The QD phosphor is a nano crystal particle composed of a core and ashell, and a core size is in the range of approximately 2-100 nm. The QDphosphor may be used as phosphor materials to emit various colors, e.g.,blue (B), yellow (Y), green (G) and red (R) by adjusting the core size.The core and shell structure of the QD phosphor may be formed byheterojunction of at least two kinds of semiconductors among group II-VIcompound semiconductors (ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe,HgTe, MgTe, etc.), group III-V compound semiconductors (GaN, GaP, GaAs,GaSb, InN, InP, InAs, InSb, AlAs, AlP, AlSb, AlS, etc.), and group IVsemiconductors (Ge, Si, Pb, etc.). An organic ligand using a materialsuch as oleic acid may be formed at the outer shell of the QD phosphorin order to terminate the molecular bonding of the shell surface,suppress the aggregation between the QD particles, improve thedispersion inside the resin such as a silicon resin or an epoxy resin,or improve the phosphor function.

As such, considering half bandwidth, peak wavelength and/or conversionefficiency, a combination of a specific red, green, yellow, or QDphosphor is provided. Thus, a white light having a high color renderingindex of 70 or more may be provided. Also, since light of severalwavelength bands is obtained through the plurality of phosphors, colorreproduction may be improved.

The main wavelength of the light emitting device may be in the range ofapproximately 360-460 nm. In this case, in order to obtain a highercolor rendering index by ensuring a wide spectrum in a visible lightband, the peak emission wavelength of the green phosphor 3012 may be inthe range of approximately 500-550 nm, and the peak emission wavelengthof the red phosphor 3014 may be in the range of approximately 610-660nm.

Preferably, when the light emitting device has the main wavelength rangeof approximately 430-460 nm, the blue light emitting device has a halfbandwidth of approximately 10-30 nm, the green phosphor has a halfbandwidth of approximately 30-100 nm, and the red phosphor has a halfbandwidth of approximately 50-150 nm.

According to another embodiment of the present invention, in addition tothe red phosphor 3012 and the green phosphor 3014, an orange yellowphosphor may be further included. In this case, the color renderingindex may be further improved. Such an embodiment is illustrated in FIG.102.

Referring to FIG. 121, the white light emitting device package 3020according to this embodiment of the present invention includes a packagemain body 3021, a blue light emitting device 3025, and a transparentresin encapsulation part 3029. A reflection cup is formed in the centerof the package main body 3021, and the blue light emitting device 3025is mounted on the bottom of the reflection cup. The transparent packagepart 3029 encapsulates the blue light emitting device 3025 within thereflection cup.

For example, the resin encapsulation part 3029 may be formed using asilicon resin, an epoxy resin, or a combination thereof. In thisembodiment, in addition to the green phosphor 3012 and the red phosphor3014 described in FIG. 101, an orange yellow phosphor 3026 is furtherincluded in the resin encapsulation part 3029.

That is, the green phosphor 3022 may be at least one phosphor selectedfrom the group consisting of M₂SiO₄:Re silicate-based phosphor, MA₂D₄:Resulfide-based phosphor, β-SiAlON:Re phosphor, and MA′₂O₄:Re′ oxide-basedphosphor. The red phosphor 3024 may be at least one selected from thegroup consisting of nitride-based phosphor, e.g., MAlSiN_(x):Re (1≦x≦5),Sr2-a-xBaaSi4-yO4-2yN4:Eux2+ (where, 0.001<x<0.2, 0≦y<2, 0≦a≦1.3),M₂Si_(3-x)Al_(x)O_(2+x)N_(4-x):Re (where, 0≦x≦0.5), orM₂Si₅N_(8-x)O_(x):Re (where, 0≦x≦0.5), and MD:Re sulfide-based phosphor.

The β-SiAlON:Re phosphor may be Si_(6-z) Al_(z)O_(z)N_(8-z):Eu_(y),Sr_(x) (where, 0≦x<0.011, 0.018<y<0.025, 0.23<z<0.35). The β-SiAlON:Rephosphor may include a crystal phase of nitride or oxynitride having aβ-Si₃N₄ crystal structure, and emit fluorescent light having a peak at agreen to red color wavelength of approximately 500-670 nm according toradiation of an excitation light source which is in an ultraviolet toblue color range having a frequency range of approximately 360-460 nm.Also, the nitride phosphor M_(x)Si_(y)N_(z):Eu (where, 1≦x≦2, 5≦y≦7,z=2x/3+4y/3) may also be used as the light emitting phosphor rangingfrom the green color to the red color.

Additionally, in this embodiment, a third phosphor 3026 is furtherincluded. The third phosphor may be an orange yellow phosphor which canemit light in a wavelength band disposed at the middle of the greencolor wavelength band and the red color wavelength band. The orangeyellow phosphor may be a silicate-based phosphor or a nitride-basedphosphor, e.g., α-SiAlON:Re phosphor.

The α-SiAlON:Re phosphor may be an oxynitride phosphor formed byactivating rare earth elements, which is characterized in that a part orall of a metal Me (where Me is Ca, or one or two kinds of Y)solid-solved in the α-SiAlON expressed as MeXSi12-(m+2)Al(m+n)OnN16-n:Re(where x, y, m and m are coefficients) is replaced with a lanthanidemetal Re which is the center of light emission.

Also, the nitride phosphor M_(x)Si_(y)N_(z):Eu (where, 1≦x≦2, 5≦y≦7,z=2x/3+4y/3) may be used as the orange yellow phosphor.

In the above-described embodiment, two or more kinds of phosphor powdersare mixed and dispersed in the single resin encapsulation part region.However, various modifications may also be made. More specifically, thetwo or three kinds of phosphors may be provided in different layerstructures. In one example, the green phosphor, the red phosphor, andthe yellow or orange yellow phosphor may be provided as a multi-layerphosphor layer by dispersing their phosphor powders at a high pressure.

As illustrated in FIG. 122, a plurality of phosphor containing resinlayer structures may be provided.

Referring to FIG. 122, like the foregoing embodiment, the white lightemitting device package 3030 according to this embodiment of the presentinvention includes a package main body 3031, a blue light emittingdevice 3035, and a transparent rein package part 3039. A reflection cupis formed at the center of the package main body 3031. The blue lightemitting device 3035 is mounted on the bottom of the reflection cup. Thetransparent resin encapsulation part 3039 encapsulates the blue lightemitting device 3035 within the reflection cup.

A resin layer including different phosphors is provided on the resinencapsuulation part 3039. That is, a wavelength conversion part may beprovided with a first resin layer 3032 containing the green phosphor, asecond resin layer 3034 containing the red phosphor, and a third resinlayer 3036 containing the yellow or orange yellow phosphor.

The phosphors used in this embodiment may be identical or similar tothose of FIG. 121.

The white light from the combination of the phosphors used herein mayobtain a high color rendering index. A further detailed description willbe made with reference to FIG. 123.

As illustrated in FIG. 123, in the case of the existing example, whenthe yellow phosphor is combined with the blue light emitting device,yellow light converted together with blue wavelength light may beobtained. Since there is almost no light in the green and red wavelengthbands when light containing entire visible light spectrum is viewed, itis difficult to ensure a color rendering index close to a natural light.In particular, the converted yellow light has a narrow half bandwidth inorder to obtain high conversion efficiency. Thus, in this case, thecolor rendering index may be further lowered.

Furthermore, in the existing example, since the white lightcharacteristic exhibited according to the single yellow color conversiondegree is easily changed, it is difficult to ensure excellent colorreproduction.

On the contrary, in the embodiment in which the blue light emittingdevice, the green phosphor (G), and the red phosphor (R) are combined,the light is emitted in the green and red color bands. Thus, a widerspectrum may be obtained in the visible light band, thereby remarkablyimproving the color rendering index. Additionally, the color renderingindex may be improved even more markedly by further including the yellowor orange yellow phosphor capable of providing the middle wavelengthband between the green color band and the red color band.

The green phosphor, the red phosphor, and the yellow or orange yellowphosphor which may be optionally added will be described below withreference to FIGS. 124 through 126.

FIGS. 124 through 126 illustrate wavelength spectrums of the phosphorsused herein; specifically, the results of light generated the blue lightemitting device (approximately 440 nm).

FIGS. 124A through 124D illustrate the spectrums of the green phosphorused herein.

FIG. 124A illustrates a spectrum of the M₂SiO₄:Re silicate-basedphosphor (where, M is at least two kinds of elements selected from Ba,Sr, Ca, and Mg, and Re is at least one selected from Eu, Y, La, Ce, Nd,Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, F, Cl, Br, and I). The convertedgreen light has a peak wavelength of approximately 530 nm and a halfbandwidth of approximately 65 nm.

FIG. 124B illustrates a spectrum of the M′A′₂O₄:Re′ oxide-based phosphor(where, M′ is at least one selected from Ba, Sr, Ca, and Mg, A′ is atleast one selected from Sc, Y, Gd, La, Lu, Al, and In, and Re′ is atleast one selected from Ce, Nd, Pm, Sm, Tb, Dy, Ho, Er, Tm, Yb, F, Cl,Br, and I). The converted green light has a peak wavelength ofapproximately 515 nm and a half bandwidth of approximately 100 nm.

FIG. 124C illustrates a spectrum of the MA₂D₄:Re sulfide-based phosphor(where, M is at least two kinds of elements selected from Ba, Sr, Ca,and Mg, A is at least one selected from Ga, Al, and In, D is at leastone selected from S, Se, and Te, and Re is at least one selected fromEu, Y, La, Ce, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, F, Cl, Br,and I). The converted green light has a peak wavelength of approximately535 nm and a half bandwidth of approximately 60 nm.

FIG. 124D illustrates a spectrum of the β-SiAlON:Re phosphor (where, Reis at least one selected from Eu, Y, La, Ce, Nd, Pm, Sm, Gd, Tb, Dy, Ho,Er, Tm, Yb, Lu, F, Cl, Br, and I). The converted green light has a peakwavelength of approximately 540 nm and a half bandwidth of approximately45 nm.

FIGS. 125A and 125B illustrate spectrums of the red phosphor usedherein.

FIG. 125A illustrates a spectrum of the M′AlSiN_(x):Re (where 1≦x≦5)nitride-based phosphor (where, M's is at least one selected from Ba, Sr,Ca, and Mg, and Re is at least one selected from Eu, Y, La, Ce, Nd, Pm,Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, F, Cl, Br, and I). The converted redlight has a peak wavelength of approximately 640 nm and a half bandwidthof approximately 85 nm.

FIG. 125B illustrates a spectrum of the M′D:Re sulfide-based phosphor(where, M′ is at least one selected from Ba, Sr, Ca, and Mg, D is atleast one selected from S, Se, and Te, and Re is at least one selectedfrom Eu, Y, La, Ce, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, F, Cl,Br, and I). The converted red light has a peak wavelength ofapproximately 655 nm and a half bandwidth of approximately 55 nm.

FIGS. 126A and 126B illustrate spectrums of the orange yellow phosphorwhich can be optionally used herein.

FIG. 126A illustrates a spectrum of the silicate-based phosphor. Theconverted yellow light has a peak wavelength of approximately 555 nm anda half bandwidth of approximately 99 nm.

FIG. 126B illustrates a spectrum of the α-SiAlON:Re phosphor (where, Reis at least one selected from Eu, Y, La, Ce, Nd, Pm, Sm, Gd, Tb, Dy, Ho,Er, Tm, Yb, Lu, F, Cl, Br, and I). The converted yellow light has a peakwavelength of approximately 580 nm and a half bandwidth of approximately35 nm.

As such, the white light having a high color rendering index of morethan 70 may be provided by a combination of a specific green phosphorand a specific red phosphor or an addition of a yellow or orange yellowphosphor to the combination, considering the bandwidth, the peakwavelength and/or the conversion efficiency.

When the main wavelength of the blue light emitting device is in therange of 430-460 nm, the peak emission wavelength of the green phosphoris in a range of 500-550 nm. The peak emission wavelength of the redphosphor is in the range of 610-660 nm. The peak emission wavelength ofthe orange yellow phosphor is in the range of 550-600 nm.

Also, when the blue light emitting device has a half bandwidth of 10 to30 nm, the green phosphor may have a half bandwidth of 30 to 100 nm, andthe red phosphor may have a half bandwidth of 50 to 150 nm. The yellowor orange yellow phosphor may have a half bandwidth of 20 to 100 nm.

A wide spectrum may be ensured in a visible light band through theselection and combination of the phosphors having those conditions, andthe superior white light having a higher color rendering index may beprovided.

Meanwhile, the red phosphor according to another embodiment of thepresent invention uses an inorganic crystal of (Sr, M)₂SiO_(4-x)N_(y) asa host material. Also, Eu is used as an activator which generates a redenergy level. Thus, a long-wavelength red light having a peak emissionwavelength in the range of 600-700 nm may be emitted. A main metalelement constituting the host material is strontium (Sr), and a metalelement M which may replace the strontium (Sr) is at least one elementamong monad and dyad elements. The emitted light color and brightnessare changed according to electron states around the main light emittingelement Eu. Therefore, the emission characteristics and physicalcharacteristics of the red phosphor may be varied by changing thecomposition of the inorganic crystal host material.

The red phosphor includes an inorganic compound expressed as thecomposition of (Sr, M)₂SiO_(4-x)N_(y):Eu. Herein, M is at least onemetal element, and x is selected within a range meeting the condition of0<x<4. Since a total charge of Sr₂SiO_(4-x)N_(y) must be zero, y=2x/3.Preferably, in order to a high-brightness red light, 0.15≦x≦3. If x isless than 0.15 or greater than 3, it is difficult to obtain a red lighthaving a desired brightness and peak emission wavelength.

Here, since M includes at least one kind of element selected from groupI elements consisting of Li, Na, K, Rb and Cs or group II elementsconsisting of Mg, Ca, Sr, and Ba, the peak emission of the red phosphormay be adjusted. In the above composition, the peak emission of the redphosphor may be adjusted by replacing a portion of Si with at least onekind of element selected from the group consisting of B, Al, Ga and In,or the group consisting of Ti, Zr, Gf, Sn, and Pb. A replacement ratioof the Si to the element may be 1/10.

In this embodiment, crystals different from silicon oxide, siliconnitride, and oxynitride are used as the host material. In this way, itis possible to obtain a long-wavelength red phosphor having a peakemission in a red color wavelength range, e.g., a wavelength range ofapproximately 600-700 nm. By replacing oxygen with nitrogen in anappropriate range in the composition, it is possible to obtain ahigh-brightness red phosphor having a peak emission in a wavelengthrange of approximately 600-620 nm.

Furthermore, compared with the existing oxide phosphor material, the redphosphor according to this embodiment of the present invention has highemission characteristics and superior thermal chemical stability becausenitrogen has a higher covalent bond characteristic than oxygen. Theexcellent thermal stability may be obtained through the stiffer crystalstructure. The splitting of the energy level within the lanthanideelements is increased by the stiff crystal structure due to nitrogen,thereby emitting light having a longer wavelength than the oxidephosphor material. That is, since the red phosphor according to thisembodiment of the present invention has high emission characteristicsand superior thermal chemical stability, the high-power high-reliabilitywhite light emitting device package may be manufactured.

Meanwhile, the method of manufacturing the red phosphor includes:preparing at least one of an Sr-containing compound, an M-containingcompound, an Eu-containing compound, an Si-containing oxide, andSi-containing nitride as a source material; and preparing sourcematerials to be measured and mixed according to a desired stoichiometry.The mixture of the source materials may be performed using one of a drymethod and a wet method.

According to the wet mixing method, the measured mixture, a ball, and asolvent are mixed. The ball is helpful in the process of mixing andgrinding the source materials. The ball used herein is a ball which isformed of silicon oxide (Si₃N₄) or zirconia (ZrO₂) or a ball which isgenerally used in mixing materials. D.I. water, alcohol such as ethanol,or an organic solvent such as n-Hexane may be used as the solvent. Thatis, the source material, the solvent, and the ball are inserted and thenthe container is sealed. The source material is then uniformly mixed for1-24 hours by using a miller or the like. After the mixing process, themixed source material is separated from the ball, and most solvent isdried at an oven through a drying process for 1-48 hours. The driedpowder is uniformly classified in a size of less than 100 micrometers byusing a metal or polymer sieve.

Meanwhile, according to the dry mixing method, source materials areinserted into a container, without using a solvent. The source materialsare uniformly mixed using a milling machine. The mixing time isapproximately 1-24 hours. At this time, if a ball is inserted into thecontainer together with the source materials, it is easier to mix thesource materials. Hence, the mixing time may be reduced. Compared withthe wet mixing method, the dry mixing method requires no solvent dryingprocess, thereby reducing the entire processing time. Like the wetmixing method, when the mixture of the source materials is completed,the mixed powders are uniformly classified in a size of less than 100micrometers by using a metal or polymer sieve.

The finally classified mixed powders are packed into a boron nitride(BN) furnace and a sintering process is performed thereupon. At thistime, the sintering process is performed in a heating furnace at atemperature of approximately 100-1,800° C. for approximately 1-24 hours.A sintering takes place in an atmosphere of 100% nitrogen gas (N2) or ina mixed nitrogen gas containing 1-10% of hydrogen gas. The synthesizedphosphor powder is uniformly ground using a grinding mixer or a grinder.Then, a post-heat treatment is performed one to three in a mannersimilar to the above-described synthesizing process, thereby improvingthe brightness of the phosphors.

Through those processes, the final red phosphor containing the inorganiccompound expressed as the composition of (Sr, M)₂SiO_(4-x)N_(y) ismanufactured. Here, at least one of M is a monad element and a dyadelement, 0<x<4, and y=2x/3.

The finally sintered phosphor powder is ground by a grinding mixer or agrinder, and grain size is controlled through a classification processin order to obtain an optimal grain size. In this case, a sieve having asize of 16 micrometers is used to obtain a red phosphor powder comprisedof particles having a uniform size of 16 micrometers or less. Theobtained phosphor powder is post-processed using D.I. water, aninorganic acid, an organic acid, or a base. In this way, it is possibleto remove impurities such as an extra glass phase contained in thephosphor, a non-reacted metal material, etc. For example, 0.1-60% ofnitric acid is added and a stirring process is performed for 1-10 hoursto extract or remove the extra impurities. Examples of the inorganicacid include a nitric acid, a sulfuric acid, a hydrogen fluoride, and aninorganic mixed solution. Meanwhile, impurities which are not removedthrough the acid processing may be removed using a base. Examples of thebase include an inorganic base, such as sodium hydroxide or potassiumhydroxide, or a mixed solution thereof. After the acid processing andthe base processing, the remaining acid or base in the phosphor slurryis cleaned using D.I. water, and a final desired phosphor powder isobtained by performing a wet classification process, a filteringprocess, and a drying process. At this time, the drying process issufficiently performed at a temperature of approximately 50-150° C.

In an embodiment of the present invention, the Sr-containing compoundmay be SrCO₃, and the Eu-containing compound may be Eu₂O₃. Also, theSi-containing oxide may be SiO₂, and the Si-containing nitride may beSi₃N₄. In the red phosphor according to the embodiment of the presentinvention, Eu₂O₃ is added to the composition of SrCO₃—SiO₂—Si₃N₄ toobtain the inorganic compound expressed as the composition ofEu_(z)Sr_(2-z)SiO_(4-x)N_(y). In this composition, z is in the range of0.01≦z≦0.2. At the concentration where the value of z is more than 0.2,the light emitting intensity is reduced by a concentration quenching.Also, at concentrations where the value of z is less than 0.01, thelight emitting intensity is reduced by the concentration deficiency ofthe activator acting as the main light emitting element.

Hereinafter, various embodiments of the present invention will bedescribed in more detail, but it will be readily apparent that thetechnical spirit and scope of the present invention is not limited tothose embodiments.

Embodiment 1

SrCO₃, SiO₂, Eu₂O₃, and Si₃N₄ as the source materials were mixed with anethanol solvent at a stoichiometric ratio by using a ball mill. Using adrier, the ethanol solvent was volatilized from thesource-material-containing mixture. The dried source-material-containingmixture was filled into the boron nitride furnace. The boron nitridefurnace where the source-material-containing mixture was filled wasinserted into a heating furnace, and an (Sr, M)₂SiO_(4-x)N_(y):Euphosphor was manufactured by performing a sintering process in a gaseousstate of an N₂ atmosphere at a temperature of 1,600° C. for 10 hours. Atthis time, the base crystal structure of the (Sr, M)₂SiO_(4-x)N_(y):Euphosphor is Sr₂SiO₄, and the composition of the host material may bechanged by replacing strontium with the metal element M. FIGS. 127through 129 illustrate the emission spectrum, the XRD spectrum, and theEDX component analysis result of the (Sr, M)₂SiO_(4-x)N_(y):Eu phosphor,respectively. The red phosphor exhibits the red light emittingcharacteristic {circle around (1)} which has the peak emission of 613 nmwhen the excitation light source is in the wavelength range of 200-500nm. The red phosphor has an orthorhombic crystal structure equal to thatof the conventional Sr₂SiO₄ phosphor. It can be seen from the EXDcomponent analysis result that the oxygen atoms and the nitrogen atomsare contained at a ratio of 44.91 At %:4.58 At %, and a part of theoxygen atoms are replaced with the nitrogen atoms.

Embodiments 2 and 3

The (Sr, M)₂SiO_(4-x)N_(y):Eu phosphor was manufactured in the samemanner as described in embodiment 1, except that an addition amount ofnitrogen was changed. FIGS. 130 and 131 illustrate the emission spectrumand the EDX component analysis result of the (Sr, M)₂SiO_(4-x)N_(y):Euphosphor when an excitation light source having a wavelength range of200-500 nm was used. As can be seen from FIGS. 130 and 131, the graph{circle around (2)} shows the emission spectrum when At % ofoxygen:nitrogen was 56.82:4.85 (x=0.43) (embodiment 2), and the graph{circle around (3)} shows the emission spectrum when At % ofoxygen:nitrogen was 42.91:25 (x=1.86) (embodiment 3). When the value ofreplacing oxygen with nitrogen was x=0.43, the peak emission of theembodiment 2 was 610 nm. When x=1.86, the peak emission of theembodiment 3 was 620 nm. That is, as the addition amount of nitrogenincreased, the peak emission of the (Sr, M)₂SiO_(4-x)N_(y):Eu phosphormanufactured herein had a longer wavelength.

Embodiments 4 Through 6

The (Sr, M)₂SiO_(4-x)N_(y):Eu phosphor was manufactured in the samemanner as described in embodiment 1, except that an addition amount (z)of europium (Eu) was increased from 0.04 to 0.06 by units of 0.01. Atthis time, the red phosphor is expressed as the composition ofEu_(z)Sr_(2-x)SiO_(4-x)SiO_(4-x)N_(y). Europium (Eu) was replaced withstrontium and the red phosphor acts as the main light emitting element.FIG. 132 illustrates the emission spectrum of the (Sr,M)_(2-x)SiO_(4-x)N_(y):Eu_(z) phosphor when the wavelength range of200-500 nm was used as the excitation light source. As can be seen fromFIG. 132, the graphs {circle around (3)}, {circle around (4)} and{circle around (5)} illustrate the emission spectrums when z=0.04(embodiment 4), z=0.05 (embodiment 5), and z=0.06 (embodiment 6),respectively. The peak emission of embodiment 4 was 610 nm; the peakemission of embodiment 5 was 612 nm; and the peak emission of theembodiment 6 was 614 nm. That is, as the addition amount of europium(Eu) increased, the wavelength of the red phosphor became longer.

Embodiments 7 and 8

The (Sr, M)₂SiO_(4-x)N_(y):Eu phosphor was manufactured in the samemanner as the embodiment 1, except that at least one of the compoundscontaining dyad metal elements such as Ba or Ca was added. Sr may bepartially replaced with dyad metal elements such as Ba or Ca. Theaddition ratio of Sr:(Ba, Ca) was 9:1.

FIG. 133A illustrates the emission spectrum of the (Sr,M)₂SiO_(4-x)N_(y):Eu phosphor when the excitation light source havingthe wavelength range of 200-500 nm was used. As can be seen from FIG.133A, the peak emission was 613 nm when Sr was 100% ({circle around(1)}); the peak emission was 610 nm when Sr:Ba were added at a ratio of90%:10% ({circle around (7)}); and the peak emission was 615 when Sr:Cawere added at a ratio of 90%:10% ({circle around (8)}).

Embodiments 9 and 10

The (Sr, M)₂SiO_(4-x)N_(y):Eu phosphor was manufactured in the samemanner as the embodiment 1, except that at least one of the compoundscontaining triad metal elements such as Al or Ga was added. Si may bepartially replaced with triad metal elements such as Al or Ga. Theaddition ratio of Si:(Al, Ga) was 9:1.

FIG. 133B illustrates the emission spectrum of the (Sr,M)₂SiO_(4-x)N_(y):Eu phosphor when the excitation light source havingthe wavelength range of 200-500 nm was used. As can be seen from FIG.133B, the peak emission was 610 nm when Si:Ga were added at a ratio of90%:10% ({circle around (9)}), and the peak emission was 615 when Si:Alwere added at a ratio of 90%:10% ({circle around (10)}).

As can be seen from embodiments 7 through 10, if Ga and Al having asmall atomic radius are replaced around europium atom the wavelengthbecomes longer; and, if Ba and Ga having a large atomic radius arereplaced, the wavelength becomes shorter.

Embodiment 11

The (Sr, M)₂SiO_(4-x)N_(y):Eu phosphor was manufactured in the samemanner as described the embodiment 1, except that manganese (Mn) wasadded together with europium (Eu). An addition amount (z) of europium(Eu) was fixed at 0.05, and an addition amount of manganese (Mn) was0.1. FIG. 134 illustrates the emission spectrum of the (Sr,M)₂SiO_(4-x)N_(y):Eu phosphor when the excitation light source havingthe wavelength range of 200-500 nm was used. In FIG. 134, the graph{circle around (5)} illustrates a case in which an addition amount (z)of europium (Eu) was 0.05 and manganese was not added, and the graph{circle around (7)} illustrates a case in which an addition amount (z)of europium (Eu) was 0.05 and an addition amount of manganese (Mn) was0.1. As can be seen from FIG. 134, the peak emission was 613 nm in bothcases {circle around (5)} and {circle around (7)}. However, the lightemitting intensity was further improved in the case {circle around (5)}where europium (Eu) only was added than the case {circle around (7)}where manganese (Mn) was added.

The following description will be made on a method of manufacturing aβ-SiAlON phosphor which can be controlled to have high brightness anddesired grain size characteristics in the above-described phosphors.

According to this embodiment of the present invention, there is provideda method of manufacturing a β-SiAlON phosphor which has a chemicalformula expressed as Si_((6-x))Al_(x)O_(y)N_((8-y)):Ln_(z), where Ln isa rare earth element, 0<x≦4.2, 0<y≦4.2, and 0<z≦1.0. In themanufacturing method according this embodiment of the present invention,a host source material includes a silicon source material containingsilicon, and an aluminum source material containing at least one of ametal aluminum and an aluminum compound. A source material mixture ismanufactured by mixing the host source material and an activator sourcematerial which activates the host material. Then, the source materialmixture is heated in a nitrogen-containing atmosphere.

According to this embodiment of the present invention, the β-SiAlONphosphor is manufactured by mixing the source material and heating thesource material in the nitrogen-containing atmosphere. The sourcematerial includes silicon, aluminum, and rare earth metal acting as anactivator.

The silicon source material is a silicon-containing source material. Asilicon metal, silicon nitride, or silicon oxide may be used as thesilicon source material.

The silicon metal may be a high-purity silicon metal which is a powderphase and contains a small amount of impurities, e.g., Fe. The particlediameter or distribution of the silicon metal powder does not directlyaffect the phosphor particles. However, due to the sintering conditionor the mixed source material, the particle diameter or distribution ofthe silicon powder affects particle size characteristics such as aparticle size or shape of the phosphor. In addition, since the emissioncharacteristic of the phosphor is affected, it is preferable that theparticle size of the silicon metal powder is 300 μm or less.

In view of the reaction, as the particle diameter of the silicon metalis getting smaller, the reaction becomes higher. However, since theemission characteristic of the phosphor is also affected by the materialto be mixed or the sintering rate, the particle diameter of the siliconmetal need not be necessarily small, and the silicon metal is notlimited to the powder phase.

One of a metal alumina and an aluminum compound containing aluminum maybe used as the aluminum source material. Alternatively, a metal aluminumand an aluminum compound may be used together as the aluminum sourcematerial. Examples of the aluminum compound containing aluminum mayinclude aluminum nitride, aluminum oxide, and aluminum hydroxide. When asilicon metal is used as the silicon source material, a metal aluminaneed not be necessarily used as the aluminum source material, and thealuminum compound only may be used.

When the metal alumina is used, it is preferable that the metal aluminais a high-purity metal alumina which is in the powder phase and containsa small amount of impurities, e.g., Fe. In the above-described view, itis preferable that the particle diameter of the metal alumina is 300 μmor less. However, since the light emission characteristics are alsoaffected by the material to be mixed or the sintering rate, the particlediameter of the metal alumina need not necessarily be small, and themetal alumina is not limited to the powder phase.

The activator source material may be any one of rare earth metalsselected from the group consisting of Eu, Ce, Sm, Yb, Dy, Pr, and Tb.Specifically, the activator source material may be oxide, such as Eu₂O₃,Sm₂O₃, Yb₂O₃, CeO, Pr₇O₁₁ and Tb₃O₄, or Eu(NO₃)₃, or EuCl₃. Preferably,the activator source material may be Eu or Ce.

The particle characteristics of the β-SiAlON phosphor can be controlledby adjusting the mixing ratio of the silicon source material and thealuminum source material. Furthermore, the particle characteristics ofthe β-SiAlON phosphor can also be controlled by adjusting the mixingratio of the silicon metal, which is contained in the silicon sourcematerial, and the silicon nitride or silicon oxide, which is containedin the silicon compound, or by adjusting the mixing ratio of the metalalumina, which is contained in the metal alumina, and the aluminumcompound. The effects of the silicon or aluminum on the source materialwill be described below in more detail in the following embodiments.

The β-SiAlON phosphor manufactured according to the embodiments of thepresent invention may be a phosphor having the chemical formula 1 below.

Si_((6-x))Al_(x)O_(y)N_((8-y)):Ln_(z)  [Chemical Formula 1]

In the chemical formula 1 above, it is preferable that Ln is a rareearth element, 0<x≦4.2, 0<y≦4.2, and 0<z≦1.0. The β-SiAlON phosphor maybe a green phosphor and have a peak wavelength in the range ofapproximately 500-570 nm.

As described above, the actuator source material, which includes therare earth element, e.g., Eu, Sm, Yb, Ce, Pr, Tb, etc., as theactivator, is measured and mixed with the aluminum source material,which includes at least one of the silicon source material containingsilicon, the metal alumina, and the aluminum compound. Then, the sourcematerial mixture is packed into a boron nitride furnace and is sinteredat a high temperature in a nitrogen-containing atmosphere. In this way,the β-SiAlON phosphor is manufactured.

The source material mixture is sintered in a high-temperature nitrogenatmosphere, and is manufactured as the phosphor. In this case, the N₂concentration in the nitrogen-containing ambient gas may be 90% or more.Also, the nitrogen-containing ambient gas pressure may be in the rangeof approximately 0.1-20 Mpa. The nitrogen atmosphere may be formed bycreating a vacuum state and introducing nitrogen-containing ambient gas.Alternatively, the nitrogen-containing ambient gas may be introduced,without making the vacuum state. The gas introduction may bediscontinuously performed.

If the source material mixture containing silicon is sintered in thenitrogen atmosphere, nitrogen reacts with silicon, and thus silicon isnitrified to thereby form SiAlON. Thus, the nitrogen gas acts as anitrogen supply source. At this time, silicon, aluminum, and anactivator source react with one another before or during thenitrification. Therefore, since SiAlON with uniform composition may bemanufactured, the brightness of the β-SiAlON phosphor is improved.

The heating at the sintering process may be performed at a hightemperature of approximately 1,850-2,150° C. In order to manufacture ahigh-brightness phosphor, the sintering process may be performed at ahigh temperature of approximately 1900-2,100° C. at a gas pressure ofapproximately 0.8 Mpa or more, although it is changed according to thecomposition of the source material. After the heating process, theheated source material mixture may be ground or classified in order tocontrol the grain size characteristics. The ground or classified sourcematerial compound may be re-sintered at a high temperature.

Hereinafter, the present invention will be described in more detail withreference to the embodiment of the β-SiAlON phosphor manufactured by theabove-described manufacturing method.

In the following embodiments, a predetermined amount of the siliconsource material and the aluminum source material as the host materialand the activator source material are mixed by a ball mill or mixer tomanufacture a mixture. The source material mixture is put into ahigh-temperature resistant container such as a BN furnace, and isinserted into an electric furnace where a high-pressure sintering andvacuum sintering are performed. The temperature is increased to 1,800°C. or more in the nitrogen-containing atmosphere under a gas pressure ofapproximately 0.2-2 Mpa at a temperature rise rate of 20° C./min orless, and the β-SiAlON phosphor is manufactured by heating the sourcematerial mixture to 1,800° C. or more.

The phosphors of the embodiments 12 through 20, which are manufacturedusing the silicon source material and the aluminum source material whilechanging their mixing ratio, and the phosphors of the comparativeexamples 1 through 3, which are manufactured using the silicon sourcematerial containing no silicon metal, are all the Eu-activated β-SiAlONphosphors, and the green phosphors having the peak wavelength in therange of approximately 520-560 nm.

Embodiment 12

Silicon nitride (Si₃N₄) and silicon metal (Si) were used as the siliconsource material, and alumina (Al₂O₃) was used as the aluminum sourcematerial. Europium oxide (Eu₂O₃) was used as the activator. 4.047 gSi₃N₄, 5.671 g Si, 0.589 g Al₂O₃, and 0.141 g Eu₂O₃ were mixed using amixer and a sieve. Then, the mixture was filled into a BN furnace andset in a pressure-resistant electric furnace. The sintering wasperformed at 500° C. under the vacuum state, and N₂ gas was introducedat 500° C. The temperature was increased from 500° C. to 1,950° C. at arate of 5° C./min in an N₂ gas atmosphere. The mixture was sintered at agas pressure of 0.8 Mpa or more at 1,950° C. for 5 hours.

After sintering, the furnace was cooled and taken out from the electricfurnace. Then, the sintered phosphor was ground, and the phosphor wasobtained using a 100-mesh sieve. The manufactured phosphor was cleanedusing hydrofluoric acid and hydrochloric acid, dispersed and then driedsufficiently. Then, the phosphor of the embodiment 12 was obtained byclassifying the phosphor by using a 50-mesh sieve.

Embodiment 13

A β-SiAlON phosphor was manufactured in the same manner as that ofembodiment 12, except that 1.349 g Si₃N₄ and 7.291 g Si were used.

Embodiment 14

A β-SiAlON phosphor was manufactured in the same manner as that ofembodiment 12, except that 6.744 g Si₃N₄ and 4.051 g Si were used.

Embodiment 15

A β-SiAlON phosphor was manufactured in the same manner as that ofembodiment 12, except that 9.442 g Si₃N₄ and 2.430 g Si were used.

Embodiment 16

A β-SiAlON phosphor was manufactured in the same manner as that ofembodiment 12, except that Si₃N₄ was not used, and 8.101 g Si only wasused as the silicon source material.

Comparative Example 1

A β-SiAlON phosphor was manufactured in the same manner as that ofembodiment 12, except that Si was not used, and 13.488 g Si₃N₄ only wasused as the silicon source material.

Embodiment 17

Silicon nitride (Si₃N₄) and silicon metal (Si) were used as the siliconsource material, and aluminum nitride (AlN) was used as the aluminumsource material. Europium oxide (Eu₂O₃) was used as the activator. 5.395g Si₃N₄, 3.241 g Si, 0.397 g AlN, and 0.137 g Eu₂O₃ were mixed using amixer and a sieve. Then, the mixture was packed into a BN furnace andset in a pressure-resistant electric furnace. Sintering was performed at1,450° C. for more than 5 hours in a nitrogen atmosphere. After cooling,the sintered material was ground. The ground sintered material waspacked into a BN furnace and set in the pressure-resistant electricfurnace. The electric furnace was heated to 500° C. under a vacuumstate, and N₂ gas was introduced at 500° C. The temperature wasincreased from 500° C. to 2,000° C. at a rate of 5° C./min in an N₂ gasatmosphere. The mixture was sintered at a gas pressure of 0.8 Mpa ormore at 2,000° C. for 5 hours.

After sintering, the furnace was cooled and taken out from the electricfurnace. Then, the sintered phosphor was ground, and the ground phosphorwas obtained using a 100-mesh sieve. The manufactured phosphor wascleaned using hydrofluoric acid and hydrochloric acid, dispersed andthen dried sufficiently. Then, the phosphor of the embodiment 17 wasobtained by classifying the phosphor by using a 50-mesh sieve.

Embodiment 18

A β-SiAlON phosphor was manufactured in the same manner as that ofembodiment 17, except that 7.554 g Si₃N₄ and 1.944 g Si were used.

Embodiment 19

A β-SiAlON phosphor was manufactured in the same manner as that ofembodiment 17, except that Si₃N₄ was not used, and 6.481 g Si only wasused as the silicon source material.

Comparative Example 2

A β-SiAlON phosphor was manufactured in the same manner as that ofembodiment 17, except that Si was not used, and 10.791 g Si₃N₄ only wasused as the silicon source material.

Embodiment 20

A β-SiAlON phosphor was manufactured in the same manner as that ofembodiment 17, except that 6.744 g Si₃N₄, and 4.051 g Si, 0.312 galuminum metal (Al) (neither Al₂O₃ nor AlN was used as the aluminumsource material), and 0.172 g Eu₂O₃ were used.

Comparative Example 3

A β-SiAlON phosphor was manufactured in the same manner as theembodiment 20, except that Si was not used as the silicon sourcematerial, 13.488 g Si₃N₄ was used, and 0.473 g Al was used.

Table 2 below shows the mixing ratios of the source materials used inthe above-described embodiments and comparative examples.

TABLE 2 Embodiment Si₃N₄ No. (g) Si (g) Al₂O₃ (g) AlN (g) Al (g) Eu₂O₃(g) Embodiment 4.047 5.671 0.589 — — 0.141 12 Embodiment 1.349 7.2910.589 — — 0.141 13 Embodiment 6.744 4.051 0.589 — — 0.141 14 Embodiment9.442 2.430 0.589 — — 0.141 15 Embodiment — 8.101 0.589 — — 0.141 16Comparative 13.488  — 0.589 — — 0.141 Example 1 Embodiment 5.395 3.241 —0.379 — 0.137 17 Embodiment 7.554 1.944 — 0.379 — 0.137 18 Embodiment —6.481 — 0.379 — 0.137 19 Comparative 10.791  — — 0.379 — 0.137 Example 2Embodiment 6.744 4.051 — — 0.312 0.172 20 Comparative 13.488  — — —0.473 0.172 Example 3

FIG. 135 illustrates the result when the phosphor of the embodiment 12was classified by the powder XRD. By referring to FIG. 135 and usingJCPDS data, it was confirmed that the manufactured phosphor was theβ-SiAlON phosphor.

The emission characteristic was measured by irradiating excited light of460 nm of the β-SiAlON phosphor. FIG. 136 illustrates the emissionspectrum results of the β-SiAlON phosphor of the embodiment 12 and theβ-SiAlON phosphor of the comparative example 1. The β-SiAlON phosphor ofthe embodiment 12 is a green phosphor which exhibits a peak emission at541 nm and has a half bandwidth of 54.7 nm. The brightness of theβ-SiAlON phosphor of the embodiment 12 is higher that that of thecomparative example 1 by 27%.

The excitation spectrum of the β-SiAlON phosphor of the embodiment 12was measured using the light emitting color of 541 nm as detectionlight. The result is illustrated in FIG. 137. It can be seen that theexcitation band exists in the ultraviolet and visible light regionaround 500 nm.

7 parts by weight of the β-SiAlON phosphor of the embodiments 12 through20 and the comparative examples 1 through 3, 3 parts by weight ofCaAlSiN₃:Eu red phosphor, and 10 parts by weight of silicon resin weremixed to form a slurry. The slurry was injected into the cup on a mountlead where a blue LED device was mounted. The injected slurry washardened at 130° C. for 1 hour. In this way, a white LED wasmanufactured using the phosphor. The brightness of the manufacturedwhite LED was measured.

Table 3 below shows the peak emission wavelength of the β-SiAlONphosphor of the embodiments 12 through 20 and the comparative examples 1through 3, and the brightness of the white LED manufactured using thesame (parts by weight).

TABLE 3 Silicon source material Aluminum Si/Si₃N₄ source Peak Embodiment(parts by material emission Bright- No. Kind weight) Kind wavelengthness Embodiment Si/Si₃N₄ 70/30 Al₂O₃ 541 127 12 Embodiment Si/Si₃N₄90/10 Al₂O₃ 541 124 13 Embodiment Si/Si₃N₄ 50/50 Al₂O₃ 541 124 14Embodiment Si/Si₃N₄ 30/70 Al₂O₃ 541 107 15 Embodiment Si — Al₂O₃ 541 11816 Comparative Si₃N₄ — Al₂O₃ 541 100 Example 1 Embodiment Si/Si₃N₄ 50/50AlN 540 113 17 Embodiment Si/Si₃N₄ 30/70 AlN 538 115 18 Embodiment Si —AlN 540 106 19 Comparative Si₃N₄ — AlN 540 100 Example 2 EmbodimentSi/Si₃N₄ 50/50 Al 540 119 20 Comparative Si₃N₄ — AlN 536 100 Example 3

It can be seen that the peak emission wavelengths of embodiments 12through 20 and the comparative examples 1 through 3 are approximately540 nm and thus the phosphors are green phosphors. The white LED usingthe phosphors of embodiments 12 through 14 exhibited a relatively highbrightness of 124 to 127.

However, the case of the embodiment 15 in which the ratio of the siliconmetal was lower than the ratio of the silicon nitride exhibited a lowerbrightness than the case of the embodiments 12 through 14 in which theratio of the silicon metal was higher than the ratio of the siliconnitride. The case of the embodiments 16 and 19 in which only Si was usedas the silicon source material exhibited a lower brightness than thecase of the embodiments 12 through 14 and 17, but exhibited a higherbrightness than the case of the embodiments 15, 17 and 18 in which theratio of the silicon metal was lower than the ratio of the siliconnitride. Thus, the higher-brightness β-SiAlON phosphor can bemanufactured using the appropriately mixed silicon source material.

The comparative examples 1 through 3 in which only Si₃N₄ is used as thesilicon source material correspond to the case in which no silicon metalis used as the host source material.

Furthermore, a high level of brightness was also obtained when thesilicon metal and the aluminum metal were used together such as inembodiment 20.

The β-SiAlON phosphor may be usefully applied to a light emitting deviceand module which provides a white light through the combination of otherphosphors.

FIGS. 138A and 138B are cross-sectional views of light emitting devicesaccording to another embodiment and modified embodiment of the presentinvention.

Referring to FIG. 138A, a bonding pad 3102 electrically connected to abonding wire 3125 is provided on the top surface of a light emittingdevice 3110. One or two bonding pads 3102 may be provided according tothe structure of the horizontal or vertical type semiconductor lightdevice, that is, a chip die 3101. Specifically, the number of thebonding pads 3102 is changed according to the structure of the chip die3101. When the chip die 3101 is provided in a vertical orvertical/horizontal structure where P polarity and N polarity are formedon the top surface and the bottom surface, respectively, the singlebonding pad 3101 is provided to be electrically connected to the Ppolarity formed on the top surface of the chip die 3101.

Also, when the chip die 3101 is provided in a horizontal orvertical/horizontal structure where both of P polarity and N polarityare formed on the top surface, two bonding pads 3102 are provided to beelectrically connected to the P polarity and the N polarity formed onthe top surface of the chip die 3101, respectively. Furthermore, thewavelength conversion part 3103 is formed of a mixture of a phosphor anda transparent resin material, such as epoxy, silicon and resin, touniformly cover the outer surface of the chip die 3101 which isdie-attached to the sub mount 3104. At this time, the wavelengthconversion part 3103 is formed by a printing method of printing atransparent resin such as silicon or epoxy, with which the phosphor ismixed, to a constant thickness. The wavelength conversion part 3103 maybe formed to cover the entire chip die 3101, or may be cured by heat orUV light which is manually provided.

The wavelength conversion part 3103 may include a phosphor materialwhich is a wavelength conversion means selected from a garnet-basedphosphor such as YAG and TAG, a silicate-based phosphor, a sulfide-basedphosphor, a nitride-based phosphor, and a QD phosphor, which is capableof converting light emitted from the chip die into a white light.Specifically, the red phosphor may include the inorganic compound or atleast one of the silicate-based phosphor, the sulfide-based phosphor,the nitride-based phosphor, and the QD phosphor, wherein the inorganiccompound is expressed as the composition of (Sr, M)₂SiO_(4-x)N_(y):Eusynthesized in the above-described embodiments 1 through 11, where M isat least one of monad or dyad elements, 0<x<4, and y=2x/3. The leadframe 3121 is electrically connected through the wire bonding 3125 to atleast one bonding pad 3102 exposed to the outside through the topsurface of the wavelength conversion part 3103.

Referring to FIG. 138A, the light emitting device package according tothis embodiment of the present invention may include the lead frame 3121and the bonding wire 3125. The lead frame 3121 is integrally providedinside a package main body (not shown), i.e., a resin structure of aninjection-molded resin material. The bonding wire 3125 has one endwire-bonded to the bonding pad 3102, and the other end wire-bonded tothe lead frame 3121.

Referring to FIG. 138B, according to a modified embodiment of the lightemitting device package, a wavelength conversion part 3103′ is formedonly on the top surface of a chip die 3101′.

The light emitting device 3110′ is mounted on the top surface of thelead frame 3121 having a negative lead and a positive lead, and the leadframe 3121 is integrally provided in the injection-molded resinencapsulation main body (not shown) in order to form a cavity which isopened upward. The light emitting device 310′ exposed to the outsidethrough the cavity of the package main body is electrically connected tothe lead frame 3121 through the metal wire 3125 with one end bonded tothe bonding pad 3102′. In this way, the light emitting device package isconstituted.

When the vertical or vertical/horizontal type light emitting device isused in the high-power light emitting device package, the phosphor layerdirectly contacts the emission surface, and thus, the phosphor isdegraded by heat generated from the light emitting device. However,since the nitride-based red phosphor or QD phosphor according to theembodiment of the present invention is more chemically stable than thesulfide-based phosphor, the reliability to the external environment suchas heat or moisture is superior and the discoloration risk is low.Therefore, the red phosphor according to the embodiment of the presentinvention may directly form the wavelength conversion part on theemission surface of the light emitting device, and the high-powerhigh-reliability white light emitting device package may bemanufactured.

FIG. 139 is a schematic cross-sectional view of a light emitting devicepackage according to another embodiment of the present invention.Referring to FIG. 139, the light emitting device package 3200 accordingto this embodiment of the present invention includes a light emittingdevice 3201 and a wavelength conversion part 3202 which is formed tocover the surface of the light emitting device 3201 and converts thewavelength of light emitted from the light emitting device 3201. To thisend, the wavelength conversion part 3202 may have a structure in which aphosphor P is dispersed within a transparent resin part. The lightemitting device package 3200 can emit white light by mixing lightconverted by the wavelength conversion part 3202 with light emitted fromthe light emitting device 3201. The light emitting device 3201 may havea structure in which an n-type semiconductor layer, a light emittinglayer, and a p-type semiconductor layer are stacked, and a firstelectrode 3203 a and a second electrode 3203 b are formed on one surfaceof the light emitting device 3201.

Referring to FIG. 139, when a surface of the light emitting device 3201where the first electrode 3203 a and the second electrode 3203 b areformed is defined as a first surface; a surface facing the first surfaceis defined as a second surface; and a surface disposed between the firstsurface and the second surface is defined as a side surface, thewavelength conversion part 3202 may be formed to cover the first surface(electrode formation surface) and the side surface of the light emittingdevice 3201. This is intended so that light is emitted from the lightemitting device 3201 in the upward direction and the lateral directionin FIG. 139. In this embodiment, the wavelength conversion part 3202 isthinly coated along the surface of the light emitting device 3201. Thismethod can obtain uniform light as a whole, compared with the method ofinjecting a phosphor into the cup of the package main body. Furthermore,the size of the device can be reduced because the wavelength conversionpart 3202 is applied directly onto the surface of the light emittingdevice 3201, and the package main body is not separately provided.

In order for electrical connection of the light emitting device 3201, afirst electrical connection part 3204 a and a second electricalconnection part 3204 b including a plating layer are used, instead ofthe lead frame. Specifically, the first and second electrical connectionparts 3204 a and 3204 b are connected to the first and second electrodes3203 a and 3203 b, and the first and second electrical connection parts3204 a and 3204 b include plating layers. The first and secondelectrical connection parts 3204 a and 3204 b are exposed to the outsidethrough the wavelength conversion part 3202 and provided as a region forwire bonding. Compared with the typical package, the light emittingdevice 3200 according to this embodiment of the present invention has asimplified structure and may be variously applied in chip-on-board (COB)or package type light emitting devices.

FIGS. 140 and 141 are schematic cross-sectional views of light emittingdevice packages according to another embodiment of the presentinvention. Referring to FIG. 140, the light emitting device package3200′ includes a light emitting device 3201 with first and secondelectrodes 3203 a and 3203 b, a wavelength conversion part 3202, andfirst and second electrical connection parts 3204 a and 3204 b. Adifference from the structure of FIG. 139 is that the resin part 3207formed on the side surface of the light emitting device 3201 is formedof a transparent resin, with the phosphor being excluded. This is doneconsidering that the intensity of light emitted to the side surface ofthe light emitting device 3201 is lower than the intensity of lightemitted to the first surface of the light emitting device 3201.

Referring to FIG. 141, the light emitting device 3200″ includes a lightemitting device 3201 with first and second electrodes 3203 a and 3203 b,a wavelength conversion part 3202, and first and second electricalconnection parts 3204 a and 3204 b. A difference from the structure ofFIG. 139 is that an underfill resin part 3206 disposed on the firstsurface of the light emitting device 3201 to surround the side surfacesof the first and second electrodes 3203 a and 3203 b is formed of atransparent resin, with the phosphor being excluded.

Various embodiments of the wavelength conversion part structure in whichphosphors are stacked in a multi-layer structure on a UV light emittingdevice or blue light emitting device will be described below withreference to FIGS. 142 and 143.

First, FIGS. 142 and 143 are cross-sectional views of a lamp-type lightemitting device package and a chip-type light emitting device packageaccording to another embodiment of the present invention, respectively.

In the lamp-type light emitting device illustrated in FIG. 142, a UVlight emitting device 3310 having a wavelength of approximately 410 nmor less may be covered by a multi-layer phosphor layer 3320 whichincludes first, second and third phosphor layers 3321, 3322 and 3323containing three kinds of phosphors excited by ultraviolet light to emitdifferent color light.

In the chip-type light emitting device illustrated in FIG. 143, a UVlight emitting device 3310 is installed inside a groove of a casing 3306on a substrate 3305. First, second and third phosphor layers 3321, 3322and 3323 containing three kinds of phosphors are formed inside thegroove of the casing 3306. The first, second and third phosphor layers3321, 3322 and 3323 constitute a multi-layer phosphor layer 3320covering the UV light emitting device 3310. An n-electrode and ap-electrode of the UV light emitting device 3310 are electricallyconnected through a wire 3303 to a metal line 3307 formed on thesubstrate 3305.

Specifically, the first phosphor layer is disposed on the UV lightemitting device, and may be formed by mixing a red phosphor with aresin. The red phosphor includes a phosphor material which is excited byultraviolet light and emits light having a peak emission wavelength ofapproximately 600-700 nm. For example, the red phosphor may include theinorganic compound or at least one of the silicate-based phosphor, thesulfide-based phosphor, the nitride-based phosphor, and the QD phosphor,wherein the inorganic compound is expressed as the composition of (Sr,M)₂SiO_(4-x)N_(y):Eu synthesized in the above-described embodiments 1through 11, where M is at least one of monad or dyad elements, 0<x<4,and y=2x/3.

The second phosphor layer is disposed on the first phosphor layer, andmay be formed by mixing a green phosphor with a resin. The greenphosphor may be formed of a phosphor material which is excited byultraviolet light and emits light having a wavelength of approximately500-550 nm. The third phosphor layer is disposed on the second phosphorlayer, may be formed by mixing a blue phosphor with a resin. The bluephosphor may be formed of a phosphor material which is excited byultraviolet light and emits light having a wavelength of approximately420-480 nm.

The ultraviolet light emitted from the UV light emitting device throughthose structures excites different kinds of the phosphors included inthe fist, second and third phosphor layers. Accordingly, red light (R),green light (G), and blue light (B) are emitted from the first, secondand third phosphor layers. Those three light colors are mixed togetherto generate the white light (W).

In particular, the phosphor layers for converting the ultraviolet lightare formed in multi-layers, i.e., three layers. The first phosphor layeremitting the red light (R) having the longest wavelength is disposed onthe UV light emitting device, and the second and third phosphor layersemitting the green light (G) and the blue light (B) having the shorterwavelengths than the red light (R) are sequentially stacked on the firstphosphor layer. Since the first phosphor layer containing the phosphoremitting the red light (R) having the lowest light conversion efficiencyis disposed closest to the UV light emitting device, the lightconversion efficiency at the first phosphor layer is relativelyincreased. Accordingly, the entire light conversion efficiency of thelight emitting device is improved.

FIGS. 144 and 145 partially illustrate the configuration of the lightemitting device according to this embodiment of the present invention.Only the light emitting device and the multi-layer phosphor layer areillustrated in FIGS. 144 and 145, and the configurations of the othersare identical to those of FIGS. 142 and 143.

The light emitting device package illustrate in FIG. 144 includes amulti-layer phosphor layer 3420 formed to cover the UV light emittingdevice 3410 having a wavelength of 410 nm or less. In this case, themulti-layer phosphor layer 3420 is provided with a double-layer phosphorlayer. Specifically, the first phosphor layer 3421 formed on the UVlight emitting device 3410 is formed by mixing a red phosphor with aresin. The red phosphor includes a phosphor material which is excited byultraviolet light and emits light having a peak emission wavelength ofapproximately 600-700 nm. For example, the red phosphor may include theinorganic compound or at least one of the silicate-based phosphor, thesulfide-based phosphor, the nitride-based phosphor, and the QD phosphor,wherein the inorganic compound is expressed as the composition of (Sr,M)₂SiO_(4-x)N_(y):Eu synthesized in the above-described embodiments 1through 11, where M is at least one of monad or dyad elements, 0<x<4,and y=2x/3. The second phosphor layer 3422 stacked on the first phosphorlayer 3421 may be formed by selectively mixing the green phosphor andthe blue phosphor with a resin.

The ultraviolet light emitted from the UV light emitting device throughthose structures excites the phosphor included in the first phosphorlayer 3421 to emit the red light (R), and excites two kinds of thephosphors included in the second phosphor layer 3422 to emit the greenlight (G) and the blue light (B). Those three color lights are mixed togenerate white light (W). As described above, the phosphor layers forconverting the ultraviolet light are formed in two layers. The firstphosphor layer 3421 emitting red light (R) having the longest wavelengthis disposed on the UV light emitting device 3410, and the secondphosphor layer 3422 emitting the green light (G) and the blue light (B)having the shorter wavelengths than the red light (R) are stacked on thefirst phosphor layer 3421. Like the previous embodiment, such amulti-layer phosphor structure improves the light conversion efficiency.

The light emitting device package illustrate in FIG. 145 includes amulti-layer phosphor layer 3420′ formed to cover the light emittingdevice 3410′ emitting blue light (B) having a wavelength of 420 nm to480 nm. The multi-layer phosphor layer 3420′ is formed in two layers.Specifically, the first phosphor layer 3421′ formed on the lightemitting device 3410′ is formed by mixing a red phosphor with a resin.The red phosphor includes a phosphor material which is excited by bluelight and emits light having a peak emission wavelength of approximately600-700 nm. For example, the red phosphor may include the inorganiccompound or at least one of the silicate-based phosphor, thesulfide-based phosphor, the nitride-based phosphor, and the QD phosphor,wherein the inorganic compound is expressed as the composition of (Sr,M)₂SiO_(4-x)N_(y):Eu synthesized in the above-described embodiments 1through 11, where M is at least one of monad or dyad elements, 0<x<4,and y=2x/3. The second phosphor layer 3422′ stacked on the firstphosphor layer 3421′ may be formed by mixing the green phosphor and/orthe yellow phosphor with a resin.

The blue light emitted from the light emitting device through thosestructures excites the phosphor included in the first phosphor layer3421′ to emit the red light (R), and excites the phosphors included inthe second phosphor layer 3422′ to emit the green light (G) and theyellow light (Y). As such, the red light (R) and the green light (G) (orthe yellow light (Y)) emitted from the multi-layer phosphor layer andthe blue light (B) emitted from the light emitting device are mixed togenerate the white light (W).

The principle of emitting the white light in the light emitting devicepackage illustrated in FIG. 145 will be described below in detail.

FIG. 146 is a schematic conceptual diagram of the light emitting devicepackage of FIG. 145. Referring to FIG. 146, blue light is emitted from ablue light source. The blue light source has a peak emission wavelengthof 420 nm to 480 nm. In particular, a blue light emitting device havinga peak emission wavelength of 420 nm to 480 nm may be used as the bluelight source. The green phosphor and the red phosphor are excited by theblue light emitted from the blue light source to emit green and redvisible light, respectively. The emitted green and red visible light ismixed with the blue light (light emitted from the blue light source)passing through the phosphors, thereby obtaining white light.

The green phosphor has a peak emission wavelength of approximately490-550 nm, and the red phosphor includes a phosphor material which isexcited by blue light and emits light having a peak emission wavelengthof approximately 600-700 nm. For example, the red phosphor may includean inorganic compound or at least one of a silicate-based phosphor, asulfide-based phosphor, a nitride-based phosphor, and a QD phosphor,wherein the inorganic compound is expressed as the composition of (Sr,M)₂SiO_(4-x)N_(y):Eu synthesized in the above-described embodiments 1through 11, where M is at least one of monad or dyad elements, 0<x<4,and y=2x/3. The respective phosphors may have high photon efficiency atthe specific emission wavelength of the blue light source. Also, therespective phosphors have considerable transparency with respect to thevisible light emitted by other phosphors. The red phosphor is excited bythe blue light emitted by the blue light source and the green lightemitted by the green phosphor, and emits red light. The red phosphor mayhave a peak excitation wavelength of approximately 420-500 nm so thatthe red phosphor is sufficiently excited by the blue light and the greenlight. Furthermore, since the red phosphor is also excited by the greenphosphor as well as the blue light source (that is, the red phosphor isexcited doubly), the quantum yield of the red phosphor is improved. Dueto the improvement in the quantum yield of the red phosphor, the entireluminous efficiency, brightness and color rendering index are alsoimproved. Moreover, if the green light which has been wasted with nopurpose (e.g., the green light leaking out to the rear of the emissionsurface) is used to excite the red phosphor, total luminous efficiencywill be further improved. The increase in the quantum efficiency mayimprove the entire brightness and color rendering index of the whitelight emitting device.

FIG. 147 is a schematic view illustrating the energy transition of thegreen phosphor (the second phosphor) and the red phosphor (the firstphosphor) used in the light emitting device package according to thisembodiment of the present invention. Referring to FIG. 147, the secondphosphor is excited by blue light of approximately 460 nm, and emitsgreen light of approximately 530 nm. Also, the first phosphor absorbs apart of the green light emitted by the second phosphor, as well as bluelight of approximately 460 nm, and emits red light of approximately 620nm. In this manner, the first phosphor is excited doubly to emit the redlight. Specifically, the first phosphor is disposed on a blue lightsource such as a blue light emitting device, and the second phosphor isdisposed on the first phosphor. In this way, the first phosphor easilyabsorbs the light emitted from the second phosphor rearwardly, and emitsred light. Accordingly the additional light emitted by the firstphosphor further improves the overall brightness of the light emittingdevice and also further improves the color rendering index of the lightemitting device. Furthermore, the light which is otherwise emittedrearward and thus wasted can be efficiently used by the first phosphor.The phosphor arrangement having the above-described layer structure maybe easily implemented because it forms a molding resin layer where therespective phosphors are dispersed.

FIG. 148 is a cross-sectional view of a light emitting device packageaccording to another embodiment of the present invention. Referring toFIG. 148, the light emitting device package 3500 includes a packagesubstrate 3531 and a light emitting diode chip 3535 mounted on thepackage substrate 3531. The package substrate 3531 may include a bottompackage substrate 3531 a in which two lead frames 3532 a and 3532 b areformed, and a top package substrate 3531 b in which the cavity isprovided. The light emitting device 3535 is mounted inside the cavityregion. Electrodes (not shown) of the light emitting device 3535 areconnected to the top surfaces of the lead frames 3532 a and 3532 bthrough wires, respectively.

A low-refractive-index region 3536 is provided to surround the lightemitting device 3535. The low-refractive-index region 3536 may be anempty space, or may be a region filled with a transparent resin having arelatively low refractive index. When the low-refractive-index region3536 is the empty space, it has a refractive index (n=1) similar to theatmosphere. On the other hand, when the low-refractive-index region 3536is formed of the transparent resin, epoxy, silicon or a mixed resinthereof may be used. In this case, the low-refractive-index region 3536may have a refractive index of approximately 1.7.

A high-refractive-index layer 3537 is formed on the low-refractive-indexregion 3536. The high-refractive-index layer 3537 has a refractive indexhigher than at least the low-refractive-index region 3536, and an unevenpattern 3537 a is formed on the top surface of the high-refractive-indexlayer 3537. Furthermore, a wavelength conversion layer 3538 is formed onthe high-refractive-index layer 3537. The wavelength conversion layer3538 includes a phosphor 3539 for converting the wavelength of lightemitted from the LED 3535. The wavelength conversion layer 3538 is aphosphor-containing resin layer, and has a refractive index lower thanthat of at least the high-refractive-index layer 3537.

The wavelength conversion layer 3538 includes at least the red phosphorwhich absorbs the light emitted from the light emitting device, andemits light having a peak emission wavelength of approximately 600-700nm. For example, the red phosphor includes the inorganic compound or atleast one of the silicate-based phosphor, the sulfide-based phosphor,the nitride-based phosphor, and the QD phosphor, wherein the inorganiccompound is expressed as the composition of (Sr, M)₂SiO_(4-x)N_(y):Eusynthesized in the above-described embodiments 1 through 11, where M isat least one of monad or dyad elements, 0<x<4, and y=2x/3.

The high-refractive-index layer 3537 used herein may be formed of aresin having a high refractive index, or may be implemented with atransparent resin layer which include high-refractive-index particles.In this case, the high-refractive-index particles may be selected fromthe group consisting of GaP, Si, TiO₂, SrTiO₃, SiC, cubic or amorphouscarbon, carbon nano tube, AlGaInP, AlGaAs, SiN, SiON, ITO, SiGe, AlN,and GaN.

The high-refractive-index layer 3537 has a high refractive index so thatphotons scattered from the phosphor particles 3539 can be totallyreflected at the interface with the low-refractive-index region 3536.The high-refractive-index layer 3537 may have a refractive index ofapproximately 1.8 or more. When the low-refractive-index region 3536 isformed of a resin having a specific refractive index, thehigh-refractive-index layer 3537 may be formed of a material having ahigher refractive index so that it can have a sufficient refractiveindex difference from the specific resin.

Although a relatively high light extraction critical angle is obtainedat the interface with the wavelength conversion layer 3538, the unevenpattern 3537 a formed on the high-refractive-index layer 3537 makes iteasier to extract light at the wavelength conversion layer 3538. Theformation period of the uneven pattern 3537 a may be in the range ofapproximately 0.001-500 μm. Also, when the refractive index differencebetween the high-refractive-index layer 3537 and the wavelengthconversion layer 3538 is excessively large, it is difficult to expectthe sufficient light extraction even by means of the uneven pattern 3537a. Hence, it is preferable that the refractive index of thehigh-refractive-index layer 3537 is 10 or less.

FIG. 149 is a schematic view explaining a light extraction mechanism inthe light emitting device package illustrated in FIG. 148. Referring toFIGS. 148 and 149, light {circle around (1)} emitted from the lightemitting device 3535 passes through the low-refractive-index region 3536and the high-refractive-index layer 3537 and is directed toward thewavelength conversion layer 3538. Although the low-refractive-indexregion 3536 has a refractive index lower than that of the nitrideconstituting the light emitting device 3535, the light emitted from thelight emitting device 3535 may be effectively extracted at thelow-refractive-index region 3536 because the uneven pattern (not shown)is formed on the surface of the light emitting device 3535. Furthermore,the light directed from the low-refractive-index region 3536 toward thehigh-refractive-index layer 3537 may be effectively extracted because itis directed to the high-refractive-index material. Since the wavelengthconversion layer 3538 has a lower refractive index than that of thehigh-refractive-index layer 3537, it has a limited light extractioncritical angle, but it may be effectively extracted by the unevenpattern formed on the surface of the high-refractive-index layer 3537.

Then, the light {circle around (1)} emitted from the LED is excited atthe phosphor particles 3539, and a portion of the excited light {circlearound (2)} may be extracted in a desired direction, i.e., in adirection upward of the package. On the other hand, another portion ofthe excited light {circle around (3)} may be directed from thewavelength conversion layer 3538 to the high-refractive-index layer 3537toward the inside of the package. Since the wavelength conversion layer3538 has a refractive index lower than that of the high-refractive-indexlayer 3537, the light {circle around (3)} directed to the inside of thepackage may be entered into the high-refractive-index layer 3537,without being almost lost. Most of the light {circle around (3)} enteredinto the high-refractive-index layer 3537 is totally reflected at theinterface with the low-refractive-index region 3536 by the highrefractive index difference. The totally reflected light {circle around(3)} is directed to the upper portion of the high-refractive-index layer3537, and may be extracted in a desired direction while passing throughthe interface between the high-refractive-index layer 3537 and thewavelength conversion layer 3538. As described above, although thehigh-refractive-index layer 3537 and the wavelength conversion layer3538 have the limited light extraction critical angle due to therefractive index difference, the light may be easily extracted by theuneven pattern 3537 a formed on the top surface of thehigh-refractive-index layer 3537.

As such, the light {circle around (3)} scattered by the phosphorparticles 3539 and directed to the inside of the package may beeffectively totally reflected in a desired upward direction by thelow-refractive-index region 3536 and the high-refractive-index layerwhere the uneven pattern 3537 a is formed on the top surface thereof.

In accordance with the embodiment of the present invention, thewavelength conversion layer 3538 including the phosphor particles isprovided at the upper portion of the light emitting device package, andthe optical structure having the low-refractivity-index region and thehigh-refractivity-index layer with the uneven pattern is provided at thelower portion of the light emitting device package. Hence, the travelingdirection of the light scattered at the phosphor particles in anomni-direction may be readjusted in the upper direction to therebyimprove the light extraction efficiency.

FIGS. 150 through 152 are cross-sectional views of a light emittingdevice package according to another embodiment of the present invention.FIG. 150 illustrates an improved structure of the wavelength conversionlayer in the light emitting device package of FIG. 148, and FIG. 151illustrates an improved structure of the package substrate. FIG. 152illustrates an improved structure of the high-refractive-index layer.The high-refractive-index layer of FIG. 152 is formed using the shape ofthe high-refractive-index particles themselves, without employing atypical molding process or etching process.

Similar to the light emitting device package of FIG. 148, the lightemitting device package 3600 of FIG. 150 includes a package substrate3641 and a light emitting diode chip 3645 mounted on the packagesubstrate 3641. The package substrate 3641 may include a bottom packagesubstrate 3531 a in which two lead frames 3642 a and 3642 b are formed,and a top package substrate 3641 b in which a cavity is provided.Electrodes (not shown) of the light emitting device 3645 are connectedto the top surfaces of the lead frames 3642 a and 3642 b through wires,respectively.

A low-refractive-index region 3646 is provided to surround the lightemitting device 3645. The low-refractive-index region 3646 may be anempty space, or may be a region filled with a transparent resin having arelatively low refractive index, e.g., epoxy or silicon resin. When thelow-refractive-index region 3646 is an empty space, thelow-refractive-index region 3646 may be provided in such a manner that alens (not shown) having a low refractive index is disposed in the emptyspace region to surround the light emitting device 3645.

A high-refractive-index layer 3647 is formed on the low-refractive-indexregion 3646. The high-refractive-index layer 3647 has a refractive indexhigher than at least the low-refractive-index region 3646, and an unevenpattern 3647 a is formed on the top surface of the high-refractive-indexlayer 3647. The uneven pattern 3647 a formed on thehigh-refractive-index layer 3647 may make it easier to extract lightfrom the wavelength conversion layer 3648 having a relatively lowrefractive index. The formation period of the uneven pattern 3647 a maybe in the range of approximately 0.001-500 μm.

Also, a non-reflective layer 3647 b may be further formed at the bottomsurface of the high-refractive-index layer 3647, i.e., at the interfacebetween the high-refractive-index layer 3647 and thelow-refractive-index region 3646. The non-reflective layer 3647 b isformed of a material which is non-reflective in the light wavelengthband of the light emitting device 3645. Due to the non-reflective layer3647 b, the light generated by the light emitting device 3645 may bemore effectively directed toward the high-reflective-index layer 3647.

A wavelength conversion layer 3648 is formed on thehigh-refractive-index layer 3647. The wavelength conversion layer 3648includes a phosphor 3649 for converting the wavelength of light emittedfrom the light emitting device 3645. The wavelength conversion layer3648 has a refractive index lower than that of at least thehigh-refractive-index layer 3647.

In this embodiment, the wavelength conversion layer 3648 may be formedby forming a typical transparent resin region and coating a phosphor3649 on the top surface thereof. In such a structure, since the layerincluding the phosphor particles 3649 is disposed on an opticalstructure including the high-refractive-index layer 3647 and thelow-refractive-index region 3646, light extraction efficiency isremarkably improved.

Furthermore, the high-refractive-index layer 3647 may be formed of aresin having a high refractive index, or may be formed of a transparentresin containing high-refractive-index particles. Thehigh-refractive-index layer 3647 has a refractive index of 1.8 or moreso that photons scattered at the phosphor particles 3649 are totallyreflected at the interface with the low-refractive-index region 3646.The high-refractive-index layer 3647 may have a refractive index of 10or less in order to facilitate light extraction at the wavelengthconversion layer 3648.

Although the package manufacturing method according to the presentinvention is not limited to the following example, when thelow-refractive-index region 3646 is formed of a transparent resin suchas epoxy or silicon resin, the low-refractive-index region 3646 may beformed by sequentially coating and curing the high-refractive-indexlayer 3647 and the wavelength conversion layer 3648. The uneven pattern3647 a formed on the high-refractive-index layer 3647 may be formed byapplying a mechanical or chemical etching process after a curingprocess, or by using a molding frame before a curing process.

Next, the light emitting device package 3600′ illustrated in FIG. 151includes a package substrate 3651 and a light emitting device 3655mounted on the package substrate 3651. The package substrate 3651includes, but is not limited to, two lead frames 3652 a and 3652 bformed on the top surface thereof, two connection pads 3654 a and 3654 bformed on the bottom surface thereof, and conductive via holes 3653 aand 3653 b connecting them.

Similar to other embodiments, the light emitting device package 3600includes a hemispherical low-refractive-index region 3656 surrounding alight emitting device 3655, a high-refractive-index layer 3657 formed onthe low-refractive-index region 3656, and a wavelength conversion layer3658 formed on the high-refractive-index layer 3657. Thehigh-refractive-index layer 3657 has a refractive index higher than thatof at least the low-refractive-index region 3656, and an uneven pattern3657 a is formed on the top surface of the high-refractive-index layer3657. The wavelength conversion layer 3658 has a refractive index lowerthan that of at least the high-refractive-index layer 3657.

In this embodiment, when the hemispherical low-refractive-index region3656 is formed of a transparent resin, it may be easily formed using aconventional molding process, e.g., a transfer molding process. In thiscase, other layers 3657 and 3658 may be formed through a moldingprocess. On the other hand, when the low-refractive-index region 3656 isprovided with an empty space, it may be implemented by forming thehigh-refractive-index layer 3657 and/or the wavelength conversion layer3658 into a desired shape through a separate molding process andattaching the high-refractive-index layer 3657 and/or the wavelengthconversion layer 3658 on the package substrate 3651. Although thehemispherical high-refractive-index layer 3657 and the hemisphericalwavelength conversion layer 3658 are exemplified, they may also beformed in various cross-sectional shapes, e.g., rectangular ortriangular.

These various shapes may also be applied to the structure of FIG. 150 ina similar manner. For example, although the high-refractive-index layer3547 having a flat shape is illustrated in FIG. 150, it may be modifiedinto a hemispherical shape or other shapes, as illustrated in FIG. 151.

Similar to the light emitting device package of FIG. 148, the lightemitting device package of FIG. 152 includes a package substrate 3661and an LED chip 3665 mounted on the package substrate 3661. The packagesubstrate 3661 may include a bottom package substrate 3661 a in whichtwo lead frames 3662 a and 3662 b are formed, and a top packagesubstrate 3661 b in which the cavity is provided.

The light emitting device 3665 is mounted inside the cavity region.Electrodes (not shown) of the light emitting device 3665 are connectedto the top surfaces of the lead frames 3662 a and 3662 b through wires,respectively.

A low-refractive-index region 3666 may be an empty space, or may be aregion filled with a transparent resin having a relatively lowrefractive index. When the low-refractive-index region 3666 is the emptyspace, it has a refractive index (n=1) similar to that of theatmosphere. On the other hand, when the low-refractive-index region 3666is formed of the transparent resin, epoxy, silicon or a mixed resinthereof may be used. In this case, the low-refractive-index region 3666may have a refractive index of approximately 1.7.

A high-refractive-index layer 3667 is formed on the low-refractive-indexregion 3666. The high-refractive-index layer 3667 has a refractive indexhigher than that of at least the low-refractive-index region 3666, andan uneven pattern 3667 a is formed by the shape of the particles.Accordingly, in this embodiment, the shape or period of the unevenpattern 3667 a is determined by the grain size or shape of thehigh-refractive-index particles. The high-refractive-index particles maybe selected from the group consisting of GaP, Si, TiO₂, SrTiO₃, SiC,cubic or amorphous carbon, carbon nano tubes, AlGaInP, AlGaAs, SiN,SiON, ITO, SiGe, AlN, and GaN.

The high-refractive-index layer 3667 used herein may be formed byarranging the high-refractive-index particles on at least the topsurface thereof in the cavity region through a separate process.Alternatively, when the low-refractive-index region 3666 is formed of aspecific resin, it may be formed by densely coating thehigh-refractive-index particles on the top surface of the resin.

A wavelength conversion layer 3668 is formed on thehigh-refractive-index layer 3667. The wavelength conversion layer 3668includes a phosphor 3669 for converting the wavelength of light emittedfrom the light emitting device 3665. The wavelength conversion layer3668 has a refractive index lower than that of at least thehigh-refractive-index layer 3667.

The uneven pattern 3667 a formed on the high-refractive-index layer 3667makes it easier to extract light from the wavelength conversion layerhaving a relatively low refractive index. Also, when the refractiveindex difference between the high-refractive-index layer 3667 and thewavelength conversion layer 3668 is excessively large, it is difficultto expect sufficient light extraction even by means of the unevenpattern 3667 a. Hence, it is preferable that the refractive index of thehigh-refractive-index layer 3667 is 10 or less.

FIG. 153 is a schematic cross-sectional view of a light emitting devicepackage according to another embodiment of the present invention. FIG.154 is a schematic perspective view of a wavelength conversion part anda control part in the light emitting device package illustrated in FIG.153.

Referring to FIGS. 153 and 154, the light emitting device package 3700according to this embodiment of the present invention includes a mainbody 3710, a light emitting device 3720, a wavelength conversion part3730, and a control part 3740. The main body 3710 may be formed of aplastic, a resin, or a ceramic. The main body 3710 includes a cavity3711 having an opened front side, and the light emitting device 3720 isaccommodated in the cavity 3711. The cavity 3711 has an inner peripheryinclined in a forward direction in order to spread light generated fromthe light emitting device 3720. The inner periphery of the cavity 3711is extending in a direction from the inside to the outside.

As illustrated, when the cavity 3711 is formed in a cylindricalstructure and thus has a circular or elliptical horizontal-section, thecavity 3711 has a cone shape in which its outside inner diameter iswider than its inside inner diameter. However, the present invention isnot limited to the above embodiment, and the cavity 3711 may have arectangular horizontal cross-section. In this case, the cavity 3711 mayhave a pyramid shape in which its outside cross-section is wider thanits inside cross-section.

The main body 3710 includes a stepped mount part 3712 in which thewavelength conversion part 3730 is mounted on the opened front side (topsurface) of the cavity 3711. The mount part 3712 is formed to be steppeddownward from the front side (top surface) of the main body 3710, sothat the wavelength conversion part 3730 may be mounted thereon. Themount part 3712 may be formed along the outer periphery of the cavity3711.

The main body 3710 includes a pair of main electrodes 3714 and 3715having one terminal exposed to the bottom surface of the cavity 3711 tobe electrically connected to the light emitting device 3720 mounted onthe main body 3710, and the other terminal exposed to the outside of themain body 3710. The light emitting device 3720 is a type of asemiconductor device which radiates light having a predeterminedwavelength when an external voltage is applied thereto. The lightemitting device package according to this embodiment of the presentinvention changes color temperature by using a single light emittingdevice, as opposed to the related art in which a plurality of lightemitting devices are used. The light emitting device 3720 is mounted onthe main body 3710 so that it is electrically connected to the pair ofthe main terminals 3714 and 3715 which are accommodated in the cavity3711 and provided inside the main body 3710.

Meanwhile, the wavelength conversion part 3730 is mounted in the mountpart 3712 of the main body 3710 to cover the cavity 3711, and changesthe wavelength of light emitted from the light emitting device 3720. Thewavelength conversion part 3730 includes a fluid containing part 3731disposed on the path of light emitted from the light emitting device3720, a transparent fluid 3732 introduced into the fluid containing part3731, and a phosphor material 3733 dispersed within the transparentfluid 3732. The wavelength conversion part 3730 controls the colortemperature by controlling the volume of the fluid containing part 3731while changing the capacity of the transparent fluid 3732 which containsthe phosphor material 3733 and is introduced into the fluid containingpart 3731. The wavelength conversion part 3730 includes at least the redphosphor which absorbs the light emitted from the light emitting device,and emits light having a peak emission wavelength of approximately600-700 nm. For example, the red phosphor includes the inorganiccompound or at least one of the silicate-based phosphor, thesulfide-based phosphor, the nitride-based phosphor, and the QD phosphor,wherein the inorganic compound is expressed as the composition of (Sr,M)₂SiO_(4-x)N_(y):Eu synthesized in the above-described embodiments 1through 11, where M is at least one of monad or dyad elements, 0<x<4,and y=2x/3.

The fluid containing part 3731 may be formed of a silicon or rubbermaterial, which has superior deformation characteristics, such ascontraction and expansion, and superior restoring characteristic. Thefluid containing part 3731 may have light transparency in order not toaffect the color temperature. Also, the fluid containing part 3731 maybe formed in a hollow tube structure which has a predetermined volumesufficient to contain the transparent fluid 3732 introduced into theinside of the fluid containing part 3731. Although the fluid containingpart 3731 having a disk-shaped structure is illustrated, the presentinvention is not limited thereto. The fluid containing part 3731 mayhave a polygonal structure, e.g., a rectangular structure, depending onthe outer cross-section shape of the cavity 3711. The transparent fluid3732 introduced into the fluid containing part 3731 may include water,oil, or resin in order to have a flowable characteristic. Thetransparent fluid 3732 is contained in the uniformly dispersed phosphormaterial 3733.

Meanwhile, the control part 3740 is connected to the wavelengthconversion part 3730, and controls the color temperature by adjustingthe volume of the fluid containing part 3731 while changing the capacityof the transparent fluid 3732. The control part 3740 includes areservoir 3741, which communicates with the fluid containing part 3731and contains the transparent fluid 3732, and an actuator 3742, which isconnected to the reservoir 3741 and adjusts the capacity of thetransparent fluid 3732 contained in the fluid containing part 3731. Thereservoir 3741 is connected to the fluid containing part 3731 andcontains a part of the transparent fluid 3732 contained in the fluidcontaining part 3731. Therefore, the transparent fluid 3732 having aflowable characteristic is not fixed in such a state that it iscontained in the fluid containing part 3731 but is movable between thefluid containing part 3731 and the reservoir 3741. In this way, thecapacity of the transparent fluid 3732 in the fluid containing part 3731may be changed. The reservoir 3741 may be formed of the same material asthe fluid containing part 3731, and may be integrally formed with thefluid containing part 3731.

The actuator 3742 is connected to the reservoir 3741 and controls thecapacity of the transparent fluid 3732 contained in the fluid containingpart 3731. That is, the capacity of the transparent fluid 3732 insidethe fluid containing part 3731 is controlled by moving the transparentfluid 3732, which is contained in the reservoir 3741 connected to theactuator 3742, toward the fluid containing part 3731, or moving thetransparent fluid 3732 from the fluid containing part 3731 to thereservoir 3741 through the expansion or contraction of the actuator3742. Examples of the actuator 3741 may include a piezo actuator (PZT),a MEMS device, and so on. The actuator 3742 is driven by an externalvoltage. To this end, the actuator 3742 includes a pair of auxiliaryterminals 3744 and 3745 whose one end is electrically connected to theactuator 3742 and whose another end is exposed to the outside of themain body 3710.

The light emitting device package may further include an electronicdevice (not shown) controlling the operation of the actuator 3742. Adescription of the detailed connection structure of the actuator 3742and the auxiliary terminals 3744 and 3745 will be omitted. Although theauxiliary terminals 3744 and 3745 exposed to the bottom of the main body3710 are illustrated, they may also be exposed to the side of the mainbody 3710. The reservoir 3741 and the actuator 3742 may be adjacent tothe cavity 3711 and buried inside the main body 3710. In this case, themain body 3710 may have a recessed receiving groove (not shown) at whichthe reservoir 3741 and the actuator 3742 are received. Accordingly, thereservoir 3741 and the actuator 3742 may be inserted into and mounted inthe receiving groove.

In the light emitting device package according to this embodiment of thepresent invention, the reservoir 3471 and the actuator 3742 are arrangedin parallel with an optical axis along a minor axis direction of themain body 3710. However, the reservoir 3741 and the actuator 3742 mayalso be arranged to be perpendicular to the optical axis along a majoraxis direction of the main body 3710. In this case, the thickness of themain body 3710 may be reduced, and the reservoir 3741 and the actuator3742 may be more effectively mounted.

The fluid containing part 3731 is mounted on the stepped surface of themount part 3712 to cover the cavity 3711. In this case, the cavity 3711of the main body 3710 is filled with a transparent resin in order toseal the light emitting device 3720 disposed within the cavity 3711. Inaddition, the cavity 3711 may be filled with air to surround the lightemitting device 3720 disposed within the cavity 3711. In this case, thelight emitting device is sealed by the fluid containing part 3731 whichis mounted to cover the cavity 3711.

A method of changing color temperature through the operations of thewavelength conversion part 3730 and the control part 37 will bedescribed below with reference to FIGS. 155 and 156. Referring to FIG.155, when external voltage is applied through the pair of the auxiliaryterminals 3744 and 3745 and the actuator 3742 performs an expansionoperation, the reservoir 3741 connected to the actuator 3742 iscontracted by the actuator 3742, and thus the volume of the reservoir3741 is reduced. At this time, the transparent fluid 3732 contained inthe reservoir 3741 is moved to the fluid containing part 3731 to therebyincrease the flow rate of the transparent fluid 3732 filling the fluidcontaining part 3731. Therefore, the fluid containing part 3731 isexpanded by the introduced transparent fluid 3732, and thus its volumeis increased. Hence, the thickness of the phosphor fluid layer disposedon the optical axis is increased as much. Since the light generated fromthe light emitting device 3720 passes through the thick phosphor fluidlayer, the color temperature of the emitted light is lowered.

Referring to FIG. 156, when the actuator 3742 performs a contractionoperation, the reservoir 3741 connected to the actuator 3742 is expandedby the actuator 3742 and thus the volume of the reservoir 3741 isincreased. At this time, the transparent fluid 3732 contained in thereservoir 3741 is moved to the reservoir 3741 to thereby decrease theflow rate of the transparent fluid 3732 filling the fluid containingpart 3731. Therefore, the fluid containing part 3731 is contracted bythe introduced transparent fluid 3732, and thus its volume is decreased.Hence, the thickness of the phosphor fluid layer disposed on the opticalaxis is decreased as well. Since the light generated from the lightemitting device 3720 passes through the thin phosphor fluid layer, thecolor temperature of the emitted light is increased.

Although the front surface (top surface) of the fluid containing part3731 which is expanded and contracted in a flat state is illustrated inthe drawings, its center portion may protrude in a dome shape. Thechange of the color temperature may be more precisely adjusted by theelectronic device (not shown) which controls the actuator 3742.Therefore, color temperature may be easily adjusted with the singlelight emitting device, and the light source may be miniaturized becauseit is unnecessary to ensure the distance for color mixture.

FIG. 157 is a cross-sectional view of a light emitting device package3800 according to another embodiment of the present invention.

Referring to FIG. 157, the light emitting device package 3800 accordingto this embodiment of the present invention includes a light emittingdevice 3811, electrode structures 3812 and 3813, a package main body3815, a translucent transparent resin 3816, and a recessed part 3818where the light emitting device 3811 is mounted.

The light emitting device 3811 is bonded to the respective first ends ofa pair of (metal) wires 3814 a and 3814 b, and the electrode structures3812 and 3813 are bonded to the second ends of the pair of wires 3814 aand 3814 b.

The light emitting device 3811 may be one of the light emitting devicesaccording to the various embodiments of the present invention.

The package main body 3815 is a structure which is injection-molded of aresin to form a cavity 3817 having a closed bottom surface and an openedtop surface.

The cavity 3817 may have a top inclined surface inclined at a certainangle, and a reflection member 3817 a may be provided on the topinclined surface of the cavity 3817. The reflection member 3817 a isformed of a metal having a high reflectivity, e.g., Al, Ag, Ni, etc., inorder to reflect light generated from the light emitting device 3811.

The pair of the electrode structures 3812 and 3813 are integrally formedand fixed to the package main body 3815, and a part of the first end topsurfaces of the electrode structures 3812 and 3813 is exposed to theoutside through the bottom surface of the cavity 3817.

The second ends of the electrode structures 3812 and 3813 are exposed tothe outer surface of the package main body 3815 so that they may beconnected to the external power supply.

The recessed part 3818 is formed by recessing the top surfaces of theelectrode structures 3812 and 3813 exposed to the bottom surface of thecavity 3817. The recessed part 3818 may be formed in the electrodestructure 3812 where the light emitting device 3811 is mounted among thepair of the electrode structures 3812 and 3813.

The recessed part 3818 is provided with a bent part which is bentdownward in the first end of the electrode structure 3812 where at leastone light emitting device 3811 is mounted. The bend part has a flatmount surface where the light emitting device 3811 is mounted, and apair of lower inclined surfaces 3812 a and 3813 c extending upward at acertain angle at the left and right sides of the mount surface andfacing the outer surface of the light emitting device 3811.

A reflection member may be provided on the lower inclined surfaces 3812a and 3813 a in order to reflect light generated from the light emittingdevice 3811.

The depth H of the recessed part 3818 may be approximately 50-400 μm,considering the height h of the light emitting device 3811. In this way,the cavity height H of the package main body 3815 may be reduced at150-500 μm. Since the amount of the translucent transparent resin whichis contained within the capacity 3817 is reduced, the manufacturingcosts are accordingly reduced and brightness is improved. Furthermore,the products may be miniaturized.

FIG. 158 is a cross-sectional view illustrating a modified embodiment ofthe light emitting device package of FIG. 157.

Unlike the recess part 3818 of the previous embodiment, the lightemitting device package according to this modified embodiment of thepresent invention includes a groove 3818 a which is recessed from thebottom surface of the cavity 3817 at a certain depth when forming thepackage main body 3815 between the pair of electrode structures 3812 and3813 facing each other.

Since the other elements are the same as the light emitting devicepackage of FIG. 157, a detailed description thereof will be omitted.

The translucent transparent resin 3816 is formed of a transparent resinmaterial such as epoxy, silicon, or resin filling the cavity 3817 inorder to cover the light emitting device 3811 and the wires 3814 a and3814 b and protect them from the external environment.

The translucent transparent resin 3816 may include a phosphor materialwhich is a wavelength conversion means selected from a garnet-basedphosphor such as YAG and TAG, a silicate-based phosphor, a sulfide-basedphosphor, a nitride-based phosphor, and a QD phosphor, which are capableof converting light emitted from the light emitting device 3811 intowhite light.

A garnet-based phosphor material including YAG and TAG may be selectedfrom (Y,Tb,Lu,Sc,La,Gd,Sm)3(Al,Ga,In,Si,Fe)5(O,S)12:Ce, and asilicate-based phosphor material may be selected from(Sr,Ba,Ca,Mg)2SiO4:(Eu,F,Cl). Also, the sulfide-based phosphor materialmay be selected from (Ca,Sr)S:Eu, (Sr,Ca,Ba)(Al,Ga)2S4:Eu. Thenitride-based phosphor may be an oxynitride phosphor formed byactivating rare earth elements. The sulfide-based phosphor may be aphosphor in which a part or all of a metal Me (where Me is Ca, or one ortwo kinds of Y) solid-solved in α-SiAlON expressed as (Sr, Ca, Si, Al,O)N:Eu (e.g., CaAlSiN4:Eu, or β-SiAlON:Eu) or Ca-α SiAlON:Eu-basedformula: MeXSi12-(m+2)Al(m+n)OnN16-n:Re (where x, y, m and n arecoefficients) is replaced with a lanthanide metal Re which is the centerof light emission.

The α-SiAlON-based phosphor may be selected from phosphor components of(Cax,My)(Si,Al)12(O,N)16 (where, M is at least one of Eu, Tb, Yb, andEr, 0.05<(x+y)<0.3, 0.02<x<0.27, and 0.03<y<0.3).

The QD phosphor is a nano crystal particle composed of a core and ashell, and a core size is in the range of approximately 2-100 nm. The QDphosphor may be used as phosphor materials to emit various colors, e.g.,blue (B), yellow (Y), green (G) and red (R) by adjusting the core size.The core and shell structure of the QD phosphor may be formed by theheterojunction of at least two kinds of semiconductors among group II-VIcompound semiconductors (ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe,HgTe, MgTe, etc.), group III-V compound semiconductors (GaN, GaP, GaAs,GaSb, InN, InP, InAs, InSb, AlAs, AlP, AlSb, AlS, etc.), and group IVsemiconductors (Ge, Si, Pb, etc.). An organic ligand using a materialsuch as oleic acid may be formed at the outer shell of the QD phosphorin order to terminate the molecular bonding of the shell surface,suppress the aggregation between the QD particles, improve thedispersion inside the resin such as a silicon resin or an epoxy resin,or improve the phosphor function.

The white light may include the yellow (Y) phosphor, the green (G)phosphor, and the red (R) phosphors in the blue light emitting device.The yellow, green and red phosphors are excited by the blue lightemitting device to emit the yellow light, the green light, and the redlight, respectively. The yellow light, the green light, and the redlight are mixed with a part of the blue light emitted from the bluelight emitting device to thereby output the white light.

Since the respective phosphors for outputting the white light have beendescribed above in detail, a further description thereof will be omittedin this modified embodiment of the present invention.

The ends of the electrode structures 3812 and 3813 facing the outersurface of the light emitting device 3811 mounted into the groove 3818 amay have lower inclined surfaces 3812 b and 3813 b where a reflectionmember is provided in order to reflect light generated from the lightemitting device 3811.

In the light emitting device packages 3800 and 3800′ having theabove-described structure, the light emitting device 3811 disposed atthe center of the cavity 3817 is mounted on the mount source of therecessed part, which is bent downward in the electrode structure 3812,or mounted in the groove 3818 a, which is recessed between the ends ofthe electrode structures 3812 and 3813 facing each other. Thus, the topsurface of the light emitting device 3811 wire-bonded to the electrodestructures 3812 and 3813 through wires 3814 a and 3814 b may beapproximately identical to the top surface height of the electrodestructures 3812 and 3813.

In this case, the maximum height of the wires 3814 a and 3814 bwire-bonded to the light emitting device 3811 may be reduced by thereduced mount height of the light emitting device 3811.

Accordingly, it is possible to reduce the filling amount of thetranslucent transparent resin 3816 contained in the cavity in order toprotect the light emitting device 3811 and the wires 3814 a and 3814 b.Also, the filling height H of the translucent transparent resin may bereduced by the reduced mount height of the light emitting device 3811.Hence, the brightness of light generated during the light emission ofthe light emitting device 3811 may be markedly improved.

Since the filling height H of the translucent transparent resin 3816contained in the cavity 3817 is reduced, the top end height of thepackage main body 3815 is reduced by the reduced filling height, therebyfurther reducing the entire package size.

FIGS. 159A to 159C are schematic views illustrating a method ofmanufacturing an external lead frame in the light emitting devicepackage according to the embodiment of the present invention.

Referring to FIG. 159A, the negative and positive electrode structures3812 and 3813 are integrally fixed to the package main body 3815 whichis mostly injection-molded out of a resin. However, the ends of theelectrode structures 3812 and 3813 are exposed to the outer surface ofthe package main body 3815 so that they may be connected to the externalpower supply.

The electrode structures 3812 and 3813 exposed downward to the outsideof the package main body 3815 are bent in a direction opposite to theemission surface which is bent through the side and/or bottom surface ofthe package to form the cavity 3817.

The electrode structures 3812 and 3813 are bent at the side and/or rearsurface (bottom) of the mount surface (bottom surface, 3819) of thepackage.

As illustrated in FIG. 159B, the end portion of the electrode structure3812 exposed to the package bottom surface 3819 is primarily bent toform the side shape of the package 3800. Then, as illustrated in FIG.159C, the end portion of the electrode structure 3812 is bent toward therear of the package bottom surface 3819. In this way, the entireelectrode structure 3812 is completely formed.

The light emitting device package may provide a white light sourcemodule which is suitable for use as an LCD backlight unit. That is, thewhite light source module according to the embodiment of the presentinvention is an LCD backlight unit and may be combined with variousoptical members (a diffusion plate, a light guide plate, a reflectionplate, a prism sheet, etc.) to constitute the backlight assembly.Exemplary white light sources are illustrated in FIGS. 160 and 161.

Referring to FIG. 160, the light source module 310 for the LCD backlightincludes a circuit board 3101, and a plurality of white light emittingdevice packages 3010 mounted on the circuit board 3101. A conductivepattern (not shown) connected to the light emitting device 3010 may beformed on the top surface of the circuit board 3101.

The white light emitting device packages 3010 may be understood as thewhite light emitting device package which has been described above withreference to FIG. 120. That is, the blue light emitting device 3015 isdirectly mounted on the circuit board 3101 in a chip on board (COB)method. Since the structure of the respective white light emittingdevice package 3010 is provided with the hemispherical resinencapsulation part 3019 having no separate reflection wall and having alens function, the white light emitting device packages 3100 may exhibita wide orientation angle. The wide orientation angle of each respectivelight source may contribute to reducing the size (thickness or width) ofthe LCD display.

Referring to FIG. 161, the light source module 3200 for the LCDbacklight includes a circuit board 3201, and a plurality of white lightemitting device packages 3020 mounted on the circuit board 3201. Thewhite light emitting device package 3020 includes a blue light emittingdevice 3025, which is mounted inside a reflection cup of a package mainbody 3021, and a resin encapsulation part 3029, which encapsulates theblue light emitting device 3025, as described above with reference toFIG. 121. Green and red phosphors 3022 and 3024 and yellow or orangeyellow phosphors 3026 are dispersed within the resin encapsulation part3029.

<Backlight Unit>

A backlight unit according to an embodiment of the present inventionincludes the above-described light emitting device package. The lightemitting device package including the semiconductor light emittingdevice may be applied as various light sources, e.g., illuminationdevices, car headlights, etc., as well as a surface light source such asa backlight unit.

Backlight units including the light emitting device packages accordingto the various embodiments of the present invention will be describedbelow.

FIG. 162 is a schematic plan view illustrating the arrangement structureof light emitting modules in a surface light source according to anembodiment of the present invention. FIG. 163 illustrates rotationarrangement method of the light emitting modules of FIG. 162.

Referring to FIG. 162, the surface light source 4000 includes first tofourth light emitting modules 4001 a to 4001 d. The first to fourthlight emitting modules 4001 a to 4001 d include a plurality of lightemitting devices 4003 and a plurality of connectors 4004 a to 4004 d,respectively. The plurality of light emitting devices 4003 are arrangedtwo-dimensionally in rows and columns to form an emission region.Specifically, when the white light emitting device is used, the surfacelight source 1900 may be used in a backlight unit, an illuminationdevice, etc. The first to fourth light emitting modules 4001 a to 4001 dmay have a square-shaped structure and have the same shape, and includethe plurality of light emitting devices 4003 and the connectors 4004 ato 4004 d arranged on an insulation substrate.

The connector 4004 a included in the first light emitting module 4001 isdisposed adjacent to one vertex of the first light emitting module 4001a. In this case, the vertex of the first light emitting module 4001 acorresponds to the center point of the triangle formed by the first tofourth light emitting modules of FIG. 162, i.e., the center point of theentire surface light source 4000. The term “adjacent” may be understoodto mean that the connector 4004 a is disposed closest to a specificvertex among four vertexes of the first light emitting module 4001 a. Aswill be described later, the specific vertex is the rotation centerpoint of the light emitting module.

The second to fourth light emitting modules 4001 b to 4001 d areprovided in such a structure that the first light emitting module 4001 ais sequentially rotated around the rotation center point at 90 degrees.That is, the plurality of light emitting devices 4003 and the connector4004 b included in the second light emitting module 4001 b are providedin such a structure that the plurality of light emitting devices 4003and the connector 4004 a included in the first light emitting module4001 a are rotated at 90 degrees in a clockwise direction. Likewise, theplurality of light emitting devices 4003 and the connector 4004 cincluded in the third light emitting module 4001 c are provided in sucha structure that the plurality of light emitting devices 4003 and theconnector 4004 b included in the second light emitting module 4001 b arerotated at 90 degrees in a clockwise direction. The fourth lightemitting module 4001 d may be arranged in the same manner. Such arotation arrangement is illustrated in FIG. 163A. In this case, therotation direction may be not the clockwise direction but thecounterclockwise direction.

Referring to FIG. 162, the connectors 4004 a to 4004 d included in thefirst to fourth light emitting modules 4001 a to 4001 d are arrangedadjacent to the center point, and their separation distance is veryclose. Accordingly, the line structure for electrical connection may besimplified. In addition, since the first to fourth light emittingmodules 4001 a to 4001 d have the 90-degree rotation arrangementstructure, the surface light source 4000 according to this embodiment ofthe present invention may be configured with only one kind of the lightemitting module. When the rotation arrangement structure is not used,the first to fourth light emitting modules 4001 a to 4001 d must havedifferent structures in order that the connectors 4004 a to 4004 d maybe arranged adjacent to the center point. Unlike the first embodiment ofthe present invention, four kinds of light emitting modules arerequired. As such, in the case of the surface light source according tothe first embodiment of the present invention, the distance between theconnectors 4004 a to 4004 d becomes short and the electrical linestructure is simplified. Thus, only one light emitting module isrequired. Consequently, the cost reduction effect may be obtainedthrough the standardization and production improvement.

FIG. 164 is a schematic plan view illustrating the arrangement structureof light emitting modules in a surface light source according to anotherembodiment of the present invention.

Referring to FIG. 164, the surface light source according to thisembodiment of the present invention includes first to fourth lightemitting modules 4011 a to 4011 d. The first to fourth light emittingmodules 4011 a to 4011 d include a plurality of light emitting devices4003 and a plurality of connectors 4004 a to 4004 d, respectively.Unlike the embodiment of FIG. 162, in the case of the surface lightsource according to the second embodiment of the present invention, theconnectors 4014 a to 4014 d are formed in regions separate from thelight emitting devices 4013. That is, FIG. 164 is a view of the surfacelight source 4010 when seen in a direction in which the connectors 4014a to 4014 d are arranged. In the first to fourth light emitting modules4011 a to 4011 d, the connectors 4014 a to 4014 d may be formed inregions opposite to the light emitting devices 4013. Accordingly, thelight emitting devices 4013 may be arranged without limitation on theconnectors 4014 a to 4014 d.

FIG. 165 is a schematic plan view illustrating the arrangement structureof light emitting modules in a surface light source according to anotherembodiment of the present invention.

Referring to FIG. 165, the surface light source 4020 according to thisembodiment of the present invention includes first to third lightemitting modules 4021 a to 4021 c. The shape of the outer boundary linesof the first to third light emitting modules 4021 a to 4021 c iscircular. A light emitting region is circular. Like the embodiment ofFIG. 162, the first to third light emitting modules 4021 a to 4021 chave the same shape. Specifically, the first to third light emittingmodules 4021 a to 4021 c have a fan shape in which their sharing vertex,i.e., the angle formed with the rotation center point, is 120 degrees(=360 degrees/3). A plurality of light emitting devices 4023 included inthe first light emitting module 4021 a are arranged two-dimensionally infirst and second directions. The angle between the first direction andthe second direction is 120 degrees. In this case, the first directionrefers to a direction of the boundary line between the first lightemitting module 4021 a and the second light emitting module 4021 b, andthe second direction refers to a direction of the boundary line betweenthe first light emitting module 4021 a and the third light emittingmodule 4021 c.

The plurality of light emitting devices 4023 and the connector 4024 bincluded in the second light emitting module 4021 b are provided in sucha structure that the plurality of light emitting devices 4023 and theconnector 4024 a included in the first light emitting module 4021 a arerotated by 120 degrees in a clockwise direction. Likewise, the pluralityof light emitting devices 4023 and the connector 4024 c included in thethird light emitting module 4021 c are provided in such a structure thatthe plurality of light emitting devices 4023 and the connector 4024 bincluded in the second light emitting module 4021 b are rotated at 120degrees in a clockwise direction. Although the circular surface lightsource 4020 divided into three parts has been described in thisembodiment of the present invention, the shape of the surface lightsource may be a regular n polygon (where n is a natural number equal toor greater than 3), e.g., a regular triangle, a regular pentagon, etc.In this case, n light emitting modules may be arranged at a rotationangle of 360 degrees/n.

FIG. 166 is a schematic plan view illustrating the arrangement structureof light emitting modules in a surface light source according to anotherembodiment of the present invention.

Referring to FIG. 166, the surface light source 4030 according to thisembodiment of the present invention has a structure similar to thesurface light source 4000 of FIG. 162. The surface light source 4030includes first to fourth light emitting modules 4031 a to 4031 d. Thefirst to fourth light emitting modules 4031 a to 4031 include aplurality of light emitting devices 4033 and a plurality of connectors4034 a to 4034 d, respectively. The second to fourth light emittingmodules 4031 b to 4031 d may be arranged in such a structure that thefirst light emitting module 4031 a is sequentially rotated at 90degrees.

In this embodiment, the plurality of light emitting devices 4033included in the first light emitting module 4031 a are arranged in rowsand columns, i.e., in x-axis and y-axis directions. An x-axis directionpitch x is different from a y-axis direction pitch y. In thisembodiment, the y-axis direction pitch y is greater than the x-axisdirection pitch x corresponding to a value which may be generallyadopted. Accordingly, the total number of the light emitting devices4033 used herein may be reduced. Specifically, the x-axis directionpitch x is approximately 26-27 mm, and the y-axis direction pitch y isapproximately 29-37 mm. Although the y-axis direction pitch y is greaterthan the x-axis direction pitch x in this embodiment, the x-axisdirection pitch x may be greater than the y-axis direction pitch yaccording to embodiments of the present invention. That is, the x-axisdirection pitch x and the y-axis direction pitch y may have any valuesonly if they are different from each other. Meanwhile, the pitch usedherein corresponds to the distance between the center points of theadjacent light emitting devices 4033 spaced apart in a certaindirection.

The arrangement structure of the light emitting devices having thedifferent x-axis and y-axis direction pitches may minimize thenon-uniform brightness as the y-axis direction pitch y increases.Although the y-axis direction pitch y is greater than the x-axisdirection pitch x in the first light emitting module 4031 a, the secondlight emitting module 4031 b is opposite to the first light emittingmodule 4031 a. Also, the third light emitting module 4031 c is oppositeto the second light emitting module 4031 b. Furthermore, the fourthlight emitting module 4031 d formed by rotating the third light emittingmodule 4031 c at 90 degrees in a clockwise direction has the same pitchstructure as that of the second light emitting module 4031 b. Since thelight emitting module has the arrangement structure opposite to theadjacent light emitting module, it is possible to minimize thenon-uniform brightness caused by the different x-axis and y-axisdirection pitches. Consequently, the surface light source 4030 mayreduce the number of the light emitting devices 4033 while maintainingthe uniformity of the brightness distribution.

In this case, the reduction of brightness caused by the reduction in thenumber of the light emitting devices 4033 may be solved by increasing anapplied current. In this way, if the arrangement of the first lightemitting module 4031 a and the area occupied by the first light emittingmodule 4031 a in the entire light emitting area are determined, thearrangement of the other light emitting modules may be determined byrotating the first light emitting module 4031 a in a clockwise orcounterclockwise direction. The brightness uniformity and the reductionin the number of the light emitting devices may be achieved, withoutregard to the rotation direction.

Although the case in which the whole shape of the surface light sourcesis square and circular has been described in the foregoing embodiments,the present invention may also be applied to rectangular surface lightsources, as illustrated in FIG. 167.

FIG. 167 is a plan view of a surface light source according to anotherembodiment of the present invention. In this embodiment, the surfacelight source 4040 has a rectangular shape. The surface light source 4040may be provided by attaching four surface light sources 4000 of FIG. 162in series. The surface light source according to this embodiment of thepresent invention may be applied to surface light sources having a sizeof 300×1,200, 600×1,200, etc., as well as 300×300 and 600×600.Furthermore, the surface light source having the above-describedstructure may also be used in a backlight unit which irradiates lightonto a rear surface of an LCD panel.

The surface light sources according to the above-described embodimentsadopt the light emitting device packages according to the variousembodiments of the present invention. The respective light emittingdevice packages include a wavelength conversion part which includes atleast a red phosphor which absorbs the light emitted from the lightemitting device, and emits light having a peak emission wavelength ofapproximately 600-700 nm. For example, the red phosphor includes aninorganic compound or at least one of a silicate-based phosphor, agarnet-based phosphor, a sulfide-based phosphor, a nitride-basedphosphor, and a QD phosphor, wherein the inorganic compound is expressedas the composition of (Sr, M)₂SiO_(4-x)N_(y):Eu synthesized in theabove-described embodiments 1 through 11, where M is at least one ofmonad or dyad elements, 0<x<4, and y=2x/3.

FIG. 168 is a cross-sectional view of a backlight unit adopting one ofthe above-described surface light sources according to the variousembodiments of the present invention.

Referring to FIG. 168, the backlight unit 5000 according to thisembodiment of the present invention may include the above-describedsurface light sources according to the various embodiments of thepresent invention. One of the embodiments will be taken as an example.The surface light source 5000 includes a plurality of light emittingdevices 5002 arranged on a substrate 5001. The light emitting devices5002 are arranged at different pitches P1 and P2. Although not shown indetail, the light emitting region of the surface light source 5000 isdivided by n, and first to n-th light emitting modules are formed in thedivided regions. The second to n-th light emitting modules are formed bysequentially rotating the first light emitting module at 360 degrees/nin a clockwise or counterclockwise direction. Although not shown, aconnector supplying a voltage to the plurality of light emitting devices5002 is arranged adjacent to the rotation center of the first to n-thlight emitting modules.

An optical sheet 5014 is disposed on the top surface of the surfacelight source. The optical sheet 5014 includes a diffusion sheet or adiffusion plate for uniformly diffusing incident light, and a lightcondensing sheet disposed on the diffusion sheet or the diffusion plateto condense incident light in a vertical direction. The optical sheet5014 may further include a protection sheet disposed on the lightcondensing sheet to protect a lower optical structure. A sidewall 5013is formed at an edge of the top surface of the substrate 5001 tosurround the light emitting devices 5002. The sidewall 5002 has aninclined surface in a direction in which the light emitting devices 5002are arranged. In addition, a reflective layer 5011 may be provided onthe top surface of the substrate 5001 to reflect light emitted from thelight emitting devices 5002 in an upward direction. Meanwhile, thearrangement intervals of the light emitting devices 5002, i.e., thepitches P1 and P2, may be less than an optical distance l. If thiscondition is not met, the brightness uniformity of the surface lightsource may be degraded, and hot spots may appear. The optical distance lmay be understood as a distance from the emission surface of the lightemitting device 5002 to the optical sheet 5014, i.e., a distance throughwhich light travels in a vertical direction.

FIG. 169 is a perspective view of a surface light source according toanother embodiment of the present invention. Referring to FIG. 169, thesurface light source 5100 includes a lower frame 5110, a light emittingdevice package 5120, a light guide plate 5130, and an optical sheet5140. The surface light source 5100 may be used in an LCD device,together with an LCD panel which displays an image by controlling thetransmittance of light. The optical sheet 5140 may be mounted on thelight guide plate 5130 to protect a diffusion plate, a diffusion sheet,a prism sheet, and a protection sheet.

The light guide plate 5130 is divided into a plurality of light guideplates. The plurality of light guide plates are disposed in parallel ina receiving space of the lower frame 5110, and the light emitting devicepackage 5120 is disposed on a side surface of the light guide plate5130. The plurality of light guide plates 5130 may be arrangedseparately, and may be arranged to be integrally connected together.

The light emitting device package 5130 includes a wavelength conversionpart where a red phosphor, a blue phosphor, a green phosphor, and ayellow phosphor are appropriately mixed with a resin material. The redphosphor includes an inorganic compound or at least one of asilicate-based phosphor, a garnet-based phosphor, a sulfide-basedphosphor, a nitride-based phosphor, and a QD phosphor, wherein theinorganic compound is expressed as the composition of (Sr,M)₂SiO_(4-x)N_(y):Eu synthesized in the above-described embodiments 1through 11, where M is at least one of monad or dyad elements, 0<x<4,and y=2x/3. Although not shown, a reflection plate may be furtherprovided under the light guide plate 5130. The surface light source maybe mounted on and fixed to the inner space of the lower frame 5110.

FIG. 170 is a schematic view a backlight unit, i.e., a surface lightsource having a plate-type light guide plate according to anotherembodiment of the present invention.

Referring to FIG. 170, the backlight unit 5200 having the plate-typelight guide plate according to this embodiment of the present inventionis a tandem-type surface light source, and includes n LED light sourcemodules 5210, and n plate-type light guide plates 5220.

Each of the n LED light source modules 5210 includes a plurality oflight emitting device packages 5212 arranged on a substrate 5211 in arow. The n LED light source modules are arranged in parallel. Theplate-type light guide plates 5220 are arranged on the sides of the nLED light source modules 5210.

In addition, the backlight unit having the plate-type light guide plates5220 may include a reflection member (not shown) which is disposed underthe LED light source modules 5210 and the plate-type light guide plates5220 to reflect light emitted from the LED light source modules 5210.

Furthermore, the backlight unit may include a diffusion sheet or anoptical sheet (not shown) on the top surface of the plate-type lightguide plates 5220. The diffusion sheet diffuses light, which isreflected at the reflection member, refracted at the plate-type lightguide plates, and emitted toward the LCD panel, in several directions.The optical sheet (not shown) such as a prism sheet functions to collectlight, which has passed through the diffusion sheet, within a frontviewing angle.

Specifically, the LED light source module 5210 may be provided with aplurality of light emitting device packages 5212 mounted in a top viewmethod. The plate-type light guide plates 5220 are arranged in adirection in which light is emitted from the LED light source, and maybe formed of a transparent material through which light may betransmitted. Compared with an edge-type light guide plate, theplate-type light guide plate has a simple shape and its mass-productionis easy. Also, it is easy to align the position of the light guide plateon the LED light source.

The plate-type light guide plate 5220 includes a light incidence part5221, a light emission part 5224, and a front end part 5222. Lightemitted from the LED light source 5210 is incident on the lightincidence part 5221. The light emission part 5224 is formed in a flatpanel having a uniform thickness and has a light emission surfacethrough which light incident from the LED light source is emitted to theLCD panel as illumination light. The front end part 5222 protrudes at anopposite side of the light emission part 5224 with respect to the lightincidence part 5221 and is thinner than the light incidence part 5221.The front end part 5222 of the plate-type light guide plate 5220 isdisposed to cover the LED light source 5210. That is, (n+1)-th LED lightsource 5210 is disposed under the front end part 5222 of the n-thplate-type light guide plate 5220. The front end part 5222 of theplate-type light guide plate 5220 has a prism-shaped bottom surface5223.

As illustrated in FIG. 170B, the light emitted from the LED package 5212is not directly emitted to the light guide plate 5220, but is scatteredand dispersed by the prism-shaped bottom surface 5223 of the front endpart 5222 of the plate-type light guide plate 5220. Due to such astructure, it is possible to remove hot spots occurring in the lightguide plate on the LED light source 5210.

FIG. 171 is a schematic perspective view explaining the plate-type lightguide plate 5220 of FIG. 170. Referring to FIG. 171, the plate-typelight guide plate 5220 includes a light incidence part 5221, a lightemission part 5224, and a front end part 5222. Light emitted from theLED light source 5210 including a plurality of LED packages 5212 isincident on the light incidence part 5221. The light emission part 5224is formed as a flat panel having a uniform thickness and has a lightemission surface through which light incident from the LED light sourceis emitted to the LCD panel (not shown) as illumination light. The frontend part 5222 is formed at an opposite side of the light emission part5224 with respect to the light incidence part 5221. The cross-section ofthe front end part 5222 has a smaller thickness than the light incidencecross-section of the light incidence part 5221.

The front end part 5222 has a prism shape 5223 for dispersing a part oflight emitted from the LED packages 5212 which are arranged thereunder.The prism shape 5223 of the front end part 5222 may be at least one of atriangular prism, a conical prism, and a hemispherical prism which iscapable of dispersing and scattering incident light.

Furthermore, the prism shape of the front end part 5222 may be formedover the front end part 5222, or may be partially formed only on the topsurface of the LED package 5212. Such a prism shape makes it possible toremove hot spots occurring in the light guide plate 5220 on the LEDpackage 5212.

Therefore, in the plate-type light guide plate 5220, by processing theprism shape 5223 on the bottom surface of the front end part 5222, it isunnecessary to separately process the diffusion sheet and the prismsheet between the LED package and the light guide plate in order todisperse hot spots occurring in the light guide plate 5220 on the LEDpackage 5212 by a part of light emitted from the LED package 5212.

A backlight unit having a plate-type light guide plate according toanother embodiment of the present invention will be described below withreference to FIGS. 172 through 178.

FIG. 172 is an exploded perspective view of the backlight unit accordingto another embodiment of the present invention, and FIG. 173 is across-sectional view taken along line I-I′ after the mounting of thebacklight unit of FIG. 172. Although the backlight unit may include aplurality of light guide plates, only two light guide plates areillustrated for convenience.

Referring to FIGS. 172 and 173, the backlight unit 5300 includes abottom cover 5310, a light guide plate 5320, a light source 5330, and afixing part 5340.

The bottom cover 5310 has a receiving space. For example, the receivingspace may be defined by a plate, which forms the bottom surface of thebottom cover 5310, and a sidewall bent at an edge of the plate.

The bottom cover 5310 may include a coupling opening or coupling part5311 to which the fixing part 5340 is connected, as will be describedlater. The coupling opening or coupling part 5311 may be a through-holethrough which the fixing part 5340 passes, or a groove into which thefixing part 5340 is inserted, as will be described later.

The light guide plate 5320 is divided into a plurality of parts. Theplurality of light guide plates 5320 are arranged in parallel in areceiving space of the bottom cover 5310.

Each of the light guide plates 5320 has a through-hole 5321 passingthrough a body part. The through-holes 5321 are disposed at edges of thelight guide plates 5320. However, the present invention is not limitedto the depicted position and number of the through-holes 5321. Thethrough-holes 5321 are disposed to correspond to the coupling part 5311.

Although the light guide plates 5320 having a rectangular shape areillustrated, the present invention is not limited thereto. For example,the light guide plates 5320 may have a triangular or hexagonal shape.

A plurality of light sources 5330 are disposed at one side of each lightguide plate 5320 to provide light to each light guide plate 5320. Eachlight source 5330 may include a light source 5331, i.e., a lightemitting device package, and a substrate 5332 having a plurality ofcircuit patterns for applying a driving voltage of the light emittingdevice package 5331.

For example, the light emitting device package 5331 may include sublight emitting devices which implement a blue color, a green color, anda red color. At this time, a blue light, a green light, and a red lightemitted from the sub light emitting devices which implement the bluecolor, the green color, and the red color may be mixed to generate awhite light. Alternatively, the light emitting device may include a bluelight emitting device and a phosphor which converts a part of the bluelight emitted from the blue light emitting device into a yellow light.At this time, the blue light and the yellow light are mixed to implementwhite light.

Since the light emitting device package and the phosphor has beendescribed above, a further description thereof will be omitted.

The light generated by the light source 5330 is incident on the sidesurface of the light guide plate 5320 and emitted upward by the totalinternal reflection of the light guide plate 5320.

The fixing part 5340 fixes the light guide plate 5320 to the bottomcover 5310 in order to prevent the movement of the light guide plate5320. The fixing part 5340 is inserted into the through-hole 5321 of thelight guide plate 5320 and fixes the light guide plate 5320 to thebottom cover 5310. In addition, the fixing part 5340 may pass throughthe through-hole 5321 of the light guide plate 5320 and penetrate thecoupling part 5311 of the light guide plate 5320, e.g., the through-holepart, or be inserted into the insertion groove.

The fixing part 5340 includes a body portion 5342, and a head portion5341 which extends from the body portion 5342.

The body portion 5342 passes through the through-hole 5321 of the lightguide plate 5320 and is coupled to the coupling part 5311. Specifically,the body portion 5342 couples the light guide plate 5320 to the bottomcover 5310, so that the light guide plate 5320 is fixed on the bottomcover 5310.

The head portion 5341 has a larger width than the body portion 5342 andthus prevents the fixing part 5340 from being completely released fromthe through-hole 5321 of the light guide plate 5320.

The head portion 5341 may have a variety of cross-sectional shapes,e.g., a semicircular shape, a semi-elliptical shape, a rectangularshape, a triangular shape, etc. When the head portion 5341 has atriangular cross-sectional shape, it is possible to minimize the contactbetween the fixing part 5340 and an optical member 5360, as will bedescribed later. Thus, it is possible to minimize the occurrence of hotspots due to the fixing part 5340.

Since the light emitting plate 5320 and the optical member 5360 arespaced apart from each other by a constant interval, the light emittedfrom the light guide plate 5320 may be uniformly provided to the opticalmember 5360. Since the head portion 5341 supports the optical member5360, it functions to maintain the interval between the light guideplate 5320 and the optical member 5360, as will be described later. Theinterval between the light guide plate 5320 and the optical member 5360may be controlled by adjusting the height of the head portion 5341.

In order to minimize the influence on image quality, the fixing part5340 may be formed of a translucent material, e.g., a transparentplastic.

In addition, a reflective member 5350 may be disposed under the lightguide plates 5320. The reflective member 5350 reflects light emitteddownward to the light guide plate 5320 and thus makes the light incidenton the light guide plate 5320. Consequently, the luminous efficiency ofthe backlight unit is improved.

The reflective member 5350 may include a through-hole 5321 and apenetration part 5351 corresponding to the coupling part 5311. Thefixing part 5340 may be coupled to the coupling part 5311 through thethrough-hole 5321 and the penetration part 5351. In this manner, whenthe reflective member 5350 is divided into a plurality of members, likethe light guide plate 5320, the plurality of reflection members 5350 maybe fixed on the bottom cover 5310 by the fixing part 5340.

In addition, the backlight unit may include the optical member 5360disposed on the light guide plate 5320. Examples of the optical member5360 may include a diffusion plate, a diffusion sheet, a prism sheet,and a protection sheet, which are disposed on the light guide plate5340.

Accordingly, when the backlight unit is provided with the plurality oflight guide plates, a local dimming effect caused by partial driving maybe further improved.

Furthermore, defects caused by the movement of the light guide platesmay be prevented by fixing the light guide plates to the bottom cover byusing the fixing part.

Moreover, uniform light may be provided to the LCD panel because theinterval between the light guide plate and the optical member isconstantly maintained by the fixing part.

FIG. 174 is a plan view of an LED backlight unit according to anotherembodiment of the present invention. FIG. 175 is a perspective viewillustrating a portion A of FIG. 174 before the coupling of a substrate,and FIG. 176 is a perspective view illustrating the portion A of FIG.174 after the coupling of the substrate. FIG. 177 is a cross-sectionalview taken along line II-II′ of FIG. 176.

Referring to FIGS. 174 through 177, the LED backlight unit according tothis embodiment of the present invention includes a bottom cover 5410, aplurality of light guide plates 5420, a substrate 5431, a plurality ofLED packages 5432, and a fixing part 5440. The bottom cover 5410 has acoupling opening or coupling part, e.g., a first through-hole 5410 a ora groove. The plurality of light guide plates 5420 are arranged on thebottom cover 5410. The substrate 5431 is disposed horizontally on thebottom surface of the bottom cover 5410 at one side of the light guideplates 5420, and includes a line for applying an external voltage, and asecond through-hole 5431 a corresponding (or facing) the firstthrough-hole 5410 a of the bottom cover 5410. The plurality of LEDpackages 5432 for providing light are mounted on the substrate 5431disposed at one side of each light guide plate 5420. The fixing part5440 is coupled to the second through-hole 5431 a of the substrate 5431and/or the first through-hole 5410 a of the bottom cover 5410, andpresses edge portions of the adjacent light guide plates 5420.

The bottom cover 5410 has the first through-hole 5410 a (or a concavecoupling groove formed in the plate) passing through the plate forming areceiving space to constitute the bottom surface and having a circular,rectangular or elliptical shape. The bottom cover 5410 forms a lowerframe using iron (Fe) or electrolytic galvanized iron (EGI).Furthermore, the bottom cover 5410 may have a side frame, i.e., asidewall formed by extending the bottom surface vertically in an upwarddirection the edge portion of the plate constituting the bottom surface.At this time, the bottom surface of the lower frame may be divided intoa plurality of regions formed in a row in order for the construction ofthe split-type backlight unit. The plurality of regions may be dividedby the concave grooves formed in one side region. The concave groovesseparating the plurality of regions corresponds to receiving grooves ofthe substrate 5431, as will be described later.

The first through-hole 5410 a on the bottom cover 5410 may have variousshapes, in addition to the circular shape, for example, an ellipticalshape or a rectangular shape. However, in this embodiment, the firstthrough-hole 5410 a may be a through-hole having a major direction with,more specifically, a through-hole having two parallel major sides andtwo minor sides formed to be connected together at both ends of the twomajor sides with a predetermined curvature. The first through-hole 5410a may be formed on the bottom cover 5410 such that the major-axisdirection (Y-axis) of the first through-hole 5410 is the same as thelight traveling direction. The coupling groove also has the samestructural characteristic as above.

In the case of forming a concave receiving groove at which the entirebottom surface of the bottom cover 5410, or the substrate 5431, isreceived, a reflective plate (not shown) is attached on the plurality ofbottom surfaces, except for the concave groove. The reflective plate isformed of a white polyester film or a film coated with a metal (Ag orAl). The reflectivity of the visible light on the reflective plate isapproximately 90-97%, and reflectivity increases when the coated film isthicker.

In this case, a plurality of reflective plates on the bottom surface ofthe bottom cover 5410 may extend such that they are located between theLED package 5432 and the light guide plate 6120 disposed adjacent toeach other on the rear surface of the LED package 5432. In this case,light provided and guided from one side of the light guide plate 5420 isagain reflected by the reflective plate, without interference of the LEDpackage 5432 disposed on the other side of the light guide plate 5420,and then provided in a direction of an optical member (not shown)disposed at an upper portion. Hence, the light reflection efficiency isimproved.

An LED light source 5430 is provided at the concave receiving groove ofthe bottom cover 5410 or one side of the light guide plate 5420. The LEDlight source 5430 includes a substrate 5431 (i.e., PCB) and an LEDpackage 5432. The substrate 5431 is disposed horizontally on the bottomsurface of the bottom cover 5410 at the concave receiving groove, andincludes a line for applying an external voltage, and a secondthrough-hole 5431 a corresponding the first through-hole 5410 a of thebottom cover 5410. The LED package 5432 is mounted on the substrate5431.

The substrate 5431 has a second through-hole 5431 a between the LEDpackages 5432. The substrate 5431 having the second through-hole 5431 ais provided on the bottom surface of the lower cover 5410 to correspondto (face) the first through-hole 5410 a of the lower cover 5410. Thesecond through-hole 5431 a formed on the substrate 5431 may be circularor elliptical, like the first through-hole 5410 a of the bottom cover5410. However, in this embodiment, the second through-hole 5431 a may bea through-hole having a major direction with, more specifically, athrough-hole having two parallel major sides and two minor sides formedto be connected together at both ends of the two major sides with apredetermined curvature. Since the major axis direction (X axis) of thesecond through-hole 5431 a is perpendicular to the light travelingdirection, the second through-hole 5431 a of the substrate 5431 isintersected with the major axis direction (Y axis) of the firstthrough-hole 5410 a of the bottom cover 5410.

The size of the second through-hole 5431 a formed on the substrate 5431,more specifically, the interval (or distance) between the two majorsides, is related to the diameter of the body of the fixing part 5440with threads. This is because the size of the second through-hole 5431 amay affect the interval between the LED package 5432 and the light guideplate 5420 which guides the light provided from the LED package 5432. Adetailed description regarding this will be made later.

The LED package 5432 includes a package main body 5433, a light emittingdevice 5435, and a pair of first and second electrode structures (notshown). The package main body 5433 is fixed to the substrate 5431 toform an external frame, and has a receiving groove. The light emittingdevice 5435 is mounted on the receiving groove of the package main body5433 to provide light. A pair of first and second electrode structures(not shown) are exposed to the receiving groove, so that the lightemitting device 5435 is mounted thereon, and is electrically connectedto the line on the substrate 5431.

When the light emitting device is a blue light emitting device, the LEDpackage 5432 may further include a resin encapsulation part 5436 formedin the receiving groove in order to provide a white light. In this case,the resin encapsulation part 5436 may include a yellow phosphor. Forexample, the resin encapsulation part 5436 may be formed by injecting agel-type epoxy resin containing a YAG-based yellow phosphor, or agel-type silicon resin containing a YAG-based yellow phosphor into thereceiving groove of the package main body 5433, and performingultraviolet curing or thermal curing thereupon.

It is apparent that the present invention is not limited to the LEDpackage 5432 including the blue light emitting device and the yellowlight emitting device. For example, the LED package 5432 may include anear ultraviolet chip, and a resin encapsulation part in which a redphosphor, a green phosphor, and a blue phosphor provided on the nearultraviolet chip are mixed, or a resin encapsulation part in which a redphosphor, a green phosphor, and a blue phosphor are sequentiallystacked. Also, the LED package 5342 may be a white LED package whichincludes an inorganic compound or at least one of a silicate-basedphosphor, a garnet-based phosphor, a sulfide-based phosphor, anitride-based phosphor, and a QD phosphor, wherein the inorganiccompound is expressed as the composition of (Sr, M)₂SiO_(4-x)N_(y):Eusynthesized in the above-described embodiments 1 through 11.

A plurality of light guide plates 5420 are provided on the bottomsurface of the bottom cover 5410 divided into a plurality of regions.The side of the light guide plate 5420 may be closely attached to thepackage main body 5433 in order to provide the light emitted from thelight emitting device 5435, which is mounted within the receiving grooveof the package main body 5433, to the light guide plate 5420 withoutloss.

The light guide plate 5420 is formed of PMMA. Since PMMA among polymermaterials has the least light absorption characteristics in a visiblelight area, it has excellent transparency and gloss. PMMA is not easilybroken or deformed because of its high mechanical hardness, and it isalso light and superior in a chemical resistance. PMMA has a hightransmittance with respect to a visible light in the range of 90-91% andhas a very small internal loss. Also, the PMMA is superior in itschemical characteristic, namely, tolerance and mechanicalcharacteristic, e.g., tensile strength, flexural strength, elongationstrength, etc.

A fixing part 5440 is coupled to the substrate 5431 between the lightguide plates 5420. The fixing part 5440 has a type of a screw formed ofa transparent material. The fixing part 5440 is coupled to the secondthrough-hole 5431 a of the substrate 5431 and the first through-hole5410 a of the bottom cover 5410, which corresponds to the secondthrough-hole 5431 a, in order to simultaneously fix the adjacent lightguide plates 5420 while maintaining a constant interval between thelight guide plates 5420 provided on both sides of the LED package 5432,i.e., the front surface through which light is emitted, and the rearsurface opposite to the front surface.

In this embodiment, the fixing part 5440 is formed of a transparentmaterial in order that light guided within the light guide plate 5420 isprovided to the upper optical member disposed without interference. Thefixing part 5440 may be formed of the same material as the light guideplate 5420.

The fixing part 5440 has a head portion and a body portion. The headportion has various shapes, e.g., a circular shape or a rectangularshape. The body portion extends from the head portion and has acylindrical shape. The fixing part 5440 may be fixed to the secondthrough-hole 5431 a of the substrate 5431 and/or the first through-hole5410 a of the bottom cover 5410 through the threads formed on the outersurface of the body portion of the fixing part 5440. The body portion ofthe fixing part 5440 may have a rectangular pillar shape.

Since the fixing part 5440 is designed so that the head portion coversthe interval between the light guide plates 5420 and partially covers anedge portion of the light guide plate 5420, the interval between thelight guide plates 5420 may be slightly changed. Also, the diameter ofthe body portion may be formed to be equal to the interval or distancebetween the two parallel major sides at the second through-hole 5431 aof the substrate 5431 and/or the first through-hole 5410 a of the bottomcover 5410.

Furthermore, in the fixing part 5440, the size of the head portion orthe diameter of the body portion may be slightly changed according tothe size of the second through-hole 5431 a of the substrate 5431. Thatthe size of the second through-hole 5431 a of the substrate 5431 issmall means that the diameter of the body portion of the fixing part5440 is small. This means that the interval between the LED package 5432and the light guide plate 5420 may be reduced.

When the fixing part 5440 is coupled to the substrate 5431 and/or thebottom cover 5410 in a screw manner, the head portion presses the upperedge portion of the light guide plate 5420 disposed adjacent to thesubstrate 5431 to which the LED package 5432 is fixed. Thus, themovement of the light guide plate 5420 may be prevented even though anexternal impact is applied.

Moreover, when the fixing part 5440 passes through the firstthrough-hole 5410 a of the bottom cover 5410, the externally exposedportion of the fixing part 5440 is additionally coupled by a nut,thereby reinforcing the coupling strength.

Consequently, since the fixing part 5440 coupled to the substrate 5431can act as a spacer between the LED package 5432 and the light guideplate 5420, it maintains the interval between the LED package 5432 andthe light guide plate 5420 is constantly maintained, thereby coping withthe contraction and/or expansion of the light guide plate 5420.

The fixing part 5440 need not necessarily be formed in a thread shape.For example, as illustrated in FIG. 173, the fixing part 5440 may passthrough the second through-hole 5431 a of the substrate 5431 and thefirst through-hole 5410 a of the bottom cover 5410 and be coupled tothem through a hook portion formed at an end portion corresponding tothe head portion of the screw, and fixed by the bottom cover 5410.

An optical member (not shown) is provided on the plurality of lightguide plates 5420 in order to enhance the optical characteristic oflight provided through the light guide plate 5420. For example, theoptical member may include a diffusion plate and a prism sheet. Thediffusion plate has a diffusion pattern for reducing the non-uniformityof light transmitted through the light guide plate 5420, and the prismsheet has a light condensing pattern for increasing the front brightnessof light.

Through the above structure, the fixing part 5440 provided between thelight guide plates 5420 fixes the light guide plates 5420 whilemaintaining the constant interval therebetween. Therefore, it ispossible to prevent the movement of the light guide plate 5420 due to anexternal impact, and to cope with the contraction of the light guideplate 5420 in a direction (X axis) perpendicular to the light travelingdirection.

In addition, the second through-hole 5431 a of the substrate 5431 formedto have the major axis direction and the minor axis direction makes itpossible to cope with the contraction of the substrate 5431 in a majoraxis direction (X axis) of the second through-hole 5431 a.

Furthermore, due to the first through-hole 5410 a of the bottom cover5410 having the major axis direction (Y axis) along the light travelingdirection and the fixing part 5440 coupled to the first through-hole5410 a, the light guide plate 5420 and the fixing part 5440 and/or thesubstrate 5431 may move together along the major axis direction (Y axis)of the first through-hole 5410 a of the bottom cover 5410 when anexpansion and/or contraction of the light guide plate 5420 occurs.Consequently, the interval between the light guide plate 5420 and theLED package 5432 is constantly maintained, thereby improving theluminescent spot and luminescent line phenomenon.

Meanwhile, an LCD display unit according to an embodiment of the presentinvention may include the LED backlight unit described in the aboveembodiments, and may further include an LCD panel (not shown) providedon the optical member.

The LCD display unit may further include a mold structure, called a mainsupport, for preventing the LCD from being distorted from an externalimpact or the like. The backlight unit is provided under the mainsupport, and the LCD panel is provided on the main support.

The LCD panel includes a thin film transistor (TFT) array substrate, acolor filter substrate, and a liquid crystal layer. The TFT arraysubstrate and the color filter substrate are attached to each other,with the liquid crystal layer interposed therebetween.

On the TFT array substrate, signal lines such as gate lines and datalines are intersected, and TFTs are formed at the intersection regionsof the data lines and the gate lines. The TFTs are configured to switchvideo signals to be transmitted from the data lines to liquid crystalcells of the liquid crystal layer, i.e., red color (R), green color (G),and blue color (B) data signals, in response to scan signals providedthrough the gate lines. In addition, pixel electrodes are formed inpixel regions between the data lines and the gate lines.

A black matrix, a color filter, and a common electrode are formed on thecolor filter substrate. The black matrix is formed corresponding to thegate lines and the data lines of the TFT array substrate. The colorfilter is formed in a region partitioned by the black matrix to providered color, green color, and blue color. The common electrode is providedon the black matrix and the color filter.

Data pads and gate pads are formed at an edge portion of the TFT arraysubstrate attached to the color filter substrate. The data pads extendfrom the data lines, and the gate pads extend from the gate lines. Agate driver and a data driver are respectively connected to the datapads and the gate pads to transfer signals.

Furthermore, a top cover is provided on the LCD panel. The top covercovers four edge portions of the LCD panel and is fixed to the sidewallof the bottom cover 5410 or the main support. The top cover is formed ofthe same material as the bottom cover 5410.

FIG. 178 is a schematic plan view of a backlight unit according toanother embodiment of the present invention. FIG. 179 is a perspectiveview illustrating embodiments of the combination of the LEDs mounted onthe LED module of FIG. 178. FIG. 180 is a graph showing the LEDdistribution, depending on a forward voltage.

Referring to FIGS. 178 through 180, the backlight unit 5500 according tothis embodiment of the present invention includes a plurality of LEDmodules 5510 and at least one driver 5530. Each of the LED modules 5510includes a plurality of LEDs 5520, and the driver 5530 adjusts thebrightness of the LEDs 5520 provided in the LED modules 5510. In thisembodiment, the following description will be made with regard to anedge method of arranging the LED modules 5510 used as a line lightsource facing one or more sides of the light guide plate 5550 along theinner surface of the frame 5540, however, the present invention is notlimited thereto. Although a direct method may also be used, it isdifferent only in the arrangement position of the LED modules.Therefore, a detailed description of the direct method will be omitted.

Since the LED module 5510 includes a plurality of LEDs 5520 to emit awhite light, it becomes a unit which can be employed as a surface lightsource or a line light source having a predetermined area. The LEDmodule 5510 includes a sub mount, such as a substrate, and a pluralityof LEDs 5520 mounted on the sub mount. The plurality of LEDs 5520 maybe, but is not limited to, a white LED.

Referring to FIG. 179, the plurality of LEDs 5520 included in each LEDmodule 5510 are mounted on the substrate and electrically connectedtogether. The plurality of LEDs 5520 included in each LED module 5510form a serially connected LED array. In this embodiment, the LED arrayprovided in each LED module 5510 is formed by a method of subdividingthe LED characteristic into predetermined sections and combining thesubdivided sections. LED unit products manufactured by packaging LEDchips have characteristics such as color coordinates corresponding to aspecific range section, brightness, forward voltage (V_(f)), andwavelength. The values of the characteristics are not identical. Thevalues of LED chips are slightly different in all LED unit products andthus exhibit a scattering characteristic. That is, the range section ofthe color coordinates and the range section of the forward voltage inLED unit products are not identical, but different in the upper limitvalue or the lower limit value. When the LED array is formed by mountinga plurality of LEDs 5520, if only LEDs having characteristicscorresponding to a specific range section are mounted, a voltagedifference (ΔV) occurs between LED modules where only LEDs having a lowforward voltage (V_(f)) are mounted, as opposed to LED modules whereonly LEDs having a high forward voltage (V_(f)) are mounted. Thus,brightness uniformity is degraded and hot spots are generated on thescreen.

In this embodiment, the forward voltage (V_(f)) of the LEDs among allLED characteristics is subdivided into a plurality of sections accordingto the LED distribution, and the LEDs having the forward voltagecorresponding to each section are alternately mounted in each section tothereby form an LED array. The forward voltage (V_(f)) refers to avoltage applied across the LED connected in a forward direction.

A detailed description regarding this will be made below with referenceto FIG. 180. FIGS. 180A and 180B are graphs showing LED distributionaccording to the forward voltage. As illustrated in FIG. 180A, when theforward voltage (V_(f)) range of the LED 5520 is narrow, it may besubdivided into two sections (section A and section B) with respect tothe center of the distribution diagram. In this case, the LEDs 5520 tobe mounted are classified into first type LEDs having the forwardvoltage corresponding to the section A, and second type LEDs having theforward voltage corresponding to the section B. The first type LEDs andthe second type LEDs are alternately mounted to form the LED array.Although an array combined in the order of ABAB . . . is illustrated inFIG. 179A, the present invention is not limited thereto. The array maybe formed by mounting the LEDs in various combination methods, forexample, in the order of AABB, ABBA, and so on.

As illustrated in FIG. 180B, when the forward voltage (V_(f)) range ofthe LED 5520 is wide, it may be subdivided into three sections (sectionA, section B, and section C). In this case, the LEDs 5520 to be mountedare classified into first type LEDs having the forward voltagecorresponding to the section A, second type LEDs having the forwardvoltage corresponding to the section B, third type LEDs having theforward voltage corresponding to the section C. The first type LEDs, thesecond type LEDs, and the third type LEDs are alternately mounted toform the LED array. Although an array combined in the order of ABCABC .. . is illustrated in FIG. 179B, the present invention is not limitedthereto. The array may be formed by mounting the LEDs in variouscombination methods, for example, in the order of ABAC, ABBC, and so on.Although the forward voltage (V_(f)) is subdivided into two or threerange sections in FIGS. 180A and 180B, the present invention is notlimited thereto. The forward voltage (V_(f)) may be subdivided in tovarious range sections.

By alternately mounting the LEDs 5520 having the forward voltage (V_(f))corresponding to each section, it is possible to predict the averagevalue of the forward voltages of the LED module 5510 including the LEDs5520, and it is also possible to reduce the scattering diagram to have aspecific range value. By reducing a deviation of the forward voltage(V_(f)) between the LEDs 5520 serially connected within the module, thevoltage difference (ΔV) between the LED modules 5510 is reduced and thusthe brightness of the unit is made uniform as a whole.

At least one driver 5530 is provided to control the brightness of theLEDs 5520 included in the LED modules 5510, and is electricallyconnected to the LED modules 5510. Although not shown, a sensor isprovided to sense light emitted from the LED. A sensed brightness andcolor quality are compared with a predefined brightness and colorquality and compensated to control the brightness of the LEDs. Also, thebacklight unit may further include a control unit connected to thedriver 5530 to control the driver 5530. The LED modules 5510 connectedto the driver 5530 are connected to one driver 5530, and each driver5530 is connected to at least two LED modules 5510. At this time, theLED modules connected to the same driver 5530 have a forward voltagehaving a small voltage difference or a substantially same This may becontrolled through the combination of the LEDs 5520 depending on thesubdivision of the forward voltage for the plurality of LEDs 5520mounted on the LED modules 5510. Therefore, the LED modules 5510 areconnected in parallel between LED modules 5510 connected to the samedriver 5530.

Referring to FIG. 178, the first LED module 5510 a and the second LEDmodule 5510 b having a small voltage difference are connected to thefirst driver 5530 a to form a connection structure. The third LED module5510 c and the fourth LED module 5510 d are connected to the thirddriver 5530 c to form a connection structure. The fifth LED module 5510e and the fifth LED module 5510 f are connected to the second driver5530 b to form a connection structure. That is, at least two LED modules5510 having a small voltage difference are integrally driven by thesingle common driver 5530. Compared with the conventional backlight unitin which separate drivers are provided in each LED module, the number ofthe drivers may be reduced, thereby contributing to the miniaturizationand slimness of the backlight unit. Also, the number ofelectric/electronic parts used in the backlight unit may be reduced.Furthermore, as the number of the drivers is reduced, the entirety ofdrivers for compensating the optical characteristics of the backlightunit may be controlled more easily, thereby improving the image quality.

FIGS. 181 and 182 illustrate various embodiments of the connectionstructure of the LED module 5510 and the driver 5530. Referring to FIG.181, the first driver 5530 a is connected to the first LED module 5510 aand the fifth LED 5510 e to form a connection structure. The seconddriver 5530 b is connected to the second LED module 5510 b and the sixthLED module 5510 f to form a connection structure. The third driver 5530c is connected to the third LED module 5510 c and the fourth LED module5510 b to form a connection structure.

In the embodiment of FIG. 182, the first LED module 5510 a and thefourth LED module 5510 d are connected to the first driver 5530 a toform a connection structure. The fifth LED module 5510 e and the sixthLED module 5510 f are connected to the second driver 5530 b to form aconnection structure. The second LED module 5510 b and the third LEDmodule 5510 c are connected to the third driver 5530 c to form aconnection structure. The LED modules 5510 electrically connected to thedrivers 5530 may have various connection structures, and the presentinvention is not limited thereto. The plurality of LED modules 5510 areelectrically connected only between the LED modules 5510 commonly usingthe drivers 5530, and are not electrically connected to LED modules 5510connected to other drivers 5530.

The surface light source and the backlight unit according to theembodiments of the present invention may include LED driver circuitswhich can be directly used with AC voltages, without any converter whichconverts AC voltages into DC voltages, and may include LED array devicesimplemented according to the LED driver circuits. The LED driver circuitand the LED array device will be described in detail with reference toFIGS. 183 through 187.

FIG. 183 illustrates an LED driver circuit according to an embodiment ofthe present invention. The LED driver circuit of FIG. 184 includes aladder network LED circuit. The ladder network circuit includes threefirst branches and three second branches. The three first branches areconnected at first middle contact points c1 and c2 between first andsecond contact points a and b, and the three second branches areconnected at second middle contact points d1 and d2 between the firstand second contact points a and b. The LED driver circuit has two middlebranches connected between the first and second middle contact points c1and d1, c2 and d2. LED devices 5608, 5609, 5610, 5611, 5612, 5613, 5614and 5615 are disposed at the first and second branches and the middlebranches.

The LED driver circuit has two current loops L1 and L2 which are drivenat different half cycles of the AC voltage. The first current loop L1includes LED devices 5608, 5609, 5610, 5611 and 5612 which are seriallyconnected to be driven at a first half cycle of the AC voltage. Thesecond current loop L2 includes LED devices 5613, 5611, 5614, 5609 and5615 which are serially connected to be driven at a second half cycle ofthe AC voltage. As such, when the AC voltage is applied, the LED devices5609 and 5611 may be driven bi-directionally.

When the order of the first contact point a, the first and secondbranches, and the middle branches is defined as m, the LED arrangementof the ladder network circuit may be described as follows. The LEDdevices 5608, 5609, 5610, 5611, 5612, 5613, 5614 and 5615 may be dividedinto a first LED group and a second LED group according to the period ofa drivable AC voltage. The first LED group includes LEDs 5608, 5609,5610, 5611 and 5612 which belong to odd-numbered (2m−1) first branches,all the middle branches, and even-numbered (2m) second branches and areserially connected. The second LED group includes LEDs 5613, 5611, 5614,5609 and 5615 which belong to even-numbered (2m) first branches, all themiddle branches, and odd-numbered (2m−1) second branches and areserially connected in a polarity direction opposite to the first LEDgroup.

Therefore, the first LED group may form the first current loop which isdriven at the first half cycle of the AC voltage, and the second LEDgroup may form the second current loop which is driven at the secondhalf cycle of the AC voltage. According to this driving method, the LEDdevices 5609 and 5611 disposed at the middle branch and commonlybelonging to the first and second LED groups may be continuouslyoperated at the entire cycles of the AC voltage.

In the LED driver circuit including the eight LED devices 5608, 5609,5610, 5611, 5612, 5613, 5614 and 5615, since the two LED devices 5610and 5614 can be driven at the entire cycles of the AC voltage, five LEDdevices continuously emit light in the practical ladder network circuit(the ratio of the number of LEDs used to the number of LEDs driven is62.5%). This value is an enhanced value compared with the typicalAC-type LED arrangement, i.e., a reverse polarity arrangement (50%) or abridge arrangement (generally 60%).

The LED driver circuit according to the embodiment of the presentinvention is different from the bridge structure in that the LED device5609 and the LED device 5611 are connected not in parallel but inseries. That is, in the LED driver circuit according to the embodimentof the present invention, since the LED devices 5610 and 5614 arearranged between the LED device 5609 and the LED device 5611, the LEDdevice 5609 and the LED device 5611 are serially connected. From thisviewpoint, the LED driver circuit according to the embodiment of thepresent invention has the ladder network structure which isfundamentally different from the bridge structure.

In the LED driver circuit according to the embodiment of the presentinvention, the connection of the LEDs driven bi-directionally isestablished not in parallel but in series by inserting the LED devices5610 and 5614 and connecting four middle contact points c1, c2, d1 andd2. Such an LED arrangement connection structure forms a single loop. Asdescribed above, in the practical driving operation, since the potentialdifferences of the LEDs are different within the loop formed by themiddle contact points, they are operated in a single series type withoutforming the current loop.

According to another embodiment of the present invention, when a loopconnecting the first and second contact points in the ladder networkstructure of FIG. 183 is defined as a stack, various LED driver circuitsmay be provided by continuously connecting a plurality of stacks. Thefirst and second middle contact points may be implemented with the samenumber of three or more, and the first and second branches may beimplemented with the same number of four or more.

FIG. 184A illustrates an LED driver circuit according to anotherembodiment of the present invention, which has four first middle contactpoints c1, c2, c3 and c4 and four second middle contact points d1, d2,d3 and d4. The LED driver circuit includes four middle branches whichsequentially connect the first and second middle contact points. Such adriver circuit may be understood as a ladder network circuit havingthree stages. In FIG. 184A, one LED device is disposed in each branch.In such an arrangement, the LEDs are arranged to have the first andsecond current loops which are driven at different half cycles of the ACvoltage. That is, the LED devices are serially arranged to have thefirst current loop along A1-C1-B2-C2-A3-C3-B4-C4-A5 at the first halfcycle of the AC voltage, and the LED devices are serially arranged tohave the second current loop along B1-C1-A2-C2-B3-C3-A4-C4-B5 at thesecond half cycle of the AC voltage.

In the LED driver circuit according to this embodiment of the presentinvention, four LED devices C1, C2, C3 and C4 disposed at the middlebranch and commonly involved in the first and second current loops maybe continuously operated at the entire cycles of the AC voltage. Assuch, in the LED driver circuit including fourteen LED devices, the fourLED devices C1, C2, C3 and C4 may be driven at the entire cycles of theAC voltage. Thus, nine LED devices continuously emit light in thepractical ladder network circuit (LED use efficiency is approximately64%). In this embodiment, the further reduction in the number of LEDsused can be expected compared with the previous embodiment.

In the driver circuit of FIGS. 183 and 184 a, although the case in whicheach of the first and second branches and the middle branch includes oneLED device has been exemplified, the first and second branches and themiddle branches may include a plurality of LED devices. Even in thiscase, the plurality of LED devices belonging to the same branches areserially connected. Specifically, when the number of LEDs of the middlebranch increases, the number of LEDs driven bi-directionally relativelyincreases. Thus, the luminous efficiency with respect to the number ofLEDs used is markedly improved. Consequently, it is possible to reducethe number of LEDs necessary to obtain the desired light emitting levelat the AC voltage.

The LED driver circuit of FIG. 184B has a structure in which two LEDdevices are serially connected to the middle branches, in addition tothe LED driver circuit of FIG. 184A. The LED devices are seriallyarranged to have a first current loop alongA1-C1-C1′-B2-C2-C2′-A3-C3-C3′-B4-C4-C4′-A5 at a first half cycle of anAC voltage, and the LED devices are serially arranged to have a secondcurrent loop along B1-C1-C1′-A2-C2-C2′-B3-C3-C3′-A4-C4-C4′-B5 at asecond half cycle of an AC voltage. In the LED driver circuit accordingto this embodiment of the present invention, eight LED devices C1, C1,C2, C2′, C3, C3′, C4 and C4′ belong to the middle branches. That is, thenumber of the LED devices C1, C1′, C2, C2′, C3, C3′, C4 and C4′ commonlyinvolved in the first and second current loops to continuously operateat the entire cycles of the AC voltage are two times larger than that ofthe LED driver circuit of FIG. 184A. Consequently, in the LED drivercircuit provided with eighteen LED devices, eight LED devices C1, C1′,C2, C2′, C3, C3′, C4 and C4′ can be driven at the entire cycles of theAC voltage. Hence, thirteen LED devices continuously emit light in thepractical ladder network circuit (LED use efficiency: approximately72%). Compared with the foregoing embodiments, the number of LEDs usedmay be further reduced.

The LED driver circuit of FIG. 184C has a structure in which LED devicesA1′, B2′ and C3′ connected in parallel are arranged at a first-stagefirst branch, a second-stage second branch, and a third-stage thirdbranch in the LED driver circuit of FIG. 184A. The LED devices areserially arranged to have a first current loop along (A1,A1′)-C1-(B2,B2′)-C2-A3-(C3,C3′)-B4-C4-A5 at a first half cycle of an ACvoltage, and the LED devices are serially arranged to have a secondcurrent loop along B1-C1-A2-C2-B3-(C3,C3′)-A4-C4-C4′-B5 (devicesindicated by parentheses are connected in parallel). Since the increasein the number of the LED devices disposed at the middle branches causesthe increase in the number of devices driven bi-directionally, it isadvantageous to improving LED use efficiency. However, when only thenumber of the LED devices disposed at the middle branches is increased,the reverse voltage applied to the LED devices belonging to the firstand second branches is increased. Therefore, when the LED devices havethe same specification, it is preferable that two or three LED devicesare disposed at the middle branches.

In a specific embodiment of the present invention, a plurality of laddernetwork circuits are provided. A second contact point of a certainladder network circuit may be serially connected to a first contactpoint of another ladder network circuit. Such an embodiment isillustrated in FIG. 186.

Referring to FIG. 185, the LED driver circuit has a structure in whichtwo ladder network circuits are serially connected. That is, a secondcontact point b1 of the first ladder network circuit is connected to afirst contact point a2 of the second ladder network circuit, and a firstcontact point a1 of the first ladder network circuit is connected to asecond contact point (i.e., an AC voltage terminal) of the second laddernetwork circuit. Also, in this embodiment, two LED devices seriallyconnected to the first branch the second branch and the middle branchare arranged.

In the LED driver circuit of FIG. 185, the LED devices are seriallyarranged to have a first current loop alongA1-A1′-C1-C1′-B2-B2′-C2-C2′-A3-A3′(the first ladder networkcircuit)-B4-B4′-C3-C3′-A5-A5′-C4-C4′-B6-B6′(the second ladder networkcircuit) at a first half cycle of an AC voltage, and the LED devices areserially arranged to have a second current loop alongB1-B1′-C1-C1′-A2-A2′-C2-C2′-B3-B3′(the first ladder networkcircuit)-A4-A4′-C3-C3′-B5-B5′-C4-C4′-A6-A6′(the second ladder networkcircuit) at a second half cycle of the AC voltage.

In the LED driver circuit according to this embodiment of the presentinvention, eight LED devices C1, C1′, C2, C2′, C3, C3′, C4, C4′ belongto the middle branches. That is, the number of the LED devices C1, C1′,C2, C2′, C3, C3′, C4 and C4′ commonly involved in the first and secondcurrent loops to continuously operate at the entire cycles of the ACvoltage are two times larger than that of the LED driver circuit of FIG.184A. As such, the LED arrangement for AC driving of the ladder networkstructure according to the embodiment of the present invention may beapplied in various manners.

In another aspect of the present invention, there is provided an LEDarray apparatus including the LED devices in which the LED drivercircuit having the various ladder network structures is implemented asdescribed above. Specifically, in the LED array apparatus according tothe embodiment of the present invention, K first LED devices (where K≦3)are arranged in parallel to have n first middle contact points (wheren≦2) to which electrodes having the same polarity are connected betweena first contact point and a second contact point. L second LED devise(where L≦3) are arranged in parallel to have n second middle contactpoints to which electrodes having the same polarity are connectedbetween the first contact point and the second contact point. Electrodeshaving opposite polarity to that of the first LED devices connected tothe first and second contact points are connected to the first andsecond contact points.

Also, in M third LED devices corresponding to the middle branches of theabove-described circuit (where Mn), electrodes having opposite polarityto that of the first and second LED devices are connected to the samem-th first and second middle contact points (where m is a positiveinteger defining the order from the first contact point to the n firstand second middle contact points).

The first and second LED devices may be arranged between the contactpoints one by one. In a similar manner, the third LED device may beconnected between the first and second contact points.

If necessary, a plurality of third LED devices may be connected betweenone or more first and second middle contact points. The third LEDdevices may be connected in series or in parallel between at least oneor more first and second middle contact points (see FIG. 184B or 184C).

In order to explain the effect that reduces the number of LEDs used inthe ladder network LED driver circuit according to the embodiment of thepresent invention, a difference in the number of LED devices requiredfor meeting a specific output condition is determined is compared withthe conventional AC type LED circuit (a bipolar circuit, a bridgecircuit, etc.).

FIG. 186A illustrates a conventional LED driver circuit, and FIGS. 186Band 186C illustrates an LED driver circuit according to an embodiment ofthe present invention.

The LED driver circuit of FIG. 186A is a reverse parallel circuit for ACdriving, in which LED devices 5630A and 5630B arranged in reverseparallel are serially connected in a plurality of stages S. As shown inTable 4, even though the number of the stages S increases, the ratio ofthe number of the continuously driven LEDs to the number of LEDs used(LED use efficiency) is 50%.

The LED driver circuit of FIG. 186B is a bridge circuit in which one LEDdevice is arranged at each branch. One stage includes a total of fiveLED devices 5640A, 5640B, 5640C, 5640D and 5640E. The LED devices may beconnected to one another in a plurality of stages in order to ensure adesired output. As shown in Table 4, the bridge network LED circuit hasa use efficiency of 60%, without regard to the number of the stages S.This is because, unlike the reverse parallel arrangement of FIG. 186A,the LED devices 5640E arranged at the middle branch can be drivencontinuously bi-directionally.

In the same manner as FIG. 184A, the ladder network LED driver circuitillustrated in FIG. 184A includes a total of eight LEDs to define twostages. Five LEDs are continuously driven to ensure a high useefficiency of 62.5%. Also, as shown in Table 4, the ladder network LEDdriver circuit is configured such that as the number of stages Sincreases, a larger number of LEDs are driven bi-directionally, leadingto a gradual increase in the LED use efficiency.

TABLE 4 Reverse parallel network Bridge network Ladder network No. ofNo. of No. No. of No. of No. of bi-direction Efficiency No. ofbi-direction Efficiency of bi-direction Efficiency stages V_(f) LEDturns (%) V_(f) LED turns (%) V_(f) LED turns (%) 1 ΔV_(f) 2 0 50  3 ·ΔV_(f) 5 1 60  5 · ΔV_(f) 8 2 62.5 2  2 · ΔV_(f) 4 0 50  6 · ΔV_(f) 10 260  7 · ΔV_(f) 11 3 63.6 3  3 · ΔV_(f) 6 0 50  9 · ΔV_(f) 15 3 60  9 ·ΔV_(f) 14 4 64.3 4  5 · ΔV_(f) 8 0 50 12 · 20 4 60 11 · ΔV_(f) 17 5 64.7ΔV_(f) 5  5 · ΔV_(f) 10 0 50 15 · 25 5 60 13 · ΔV_(f) 20 6 65 ΔV_(f) 6 6 · ΔV_(f) 12 0 50 18 · 30 6 60 15 · ΔV_(f) 23 7 65.2 ΔV_(f) 7  7 ·ΔV_(f) 14 0 50 21 · 35 7 60 17 · ΔV_(f) 26 8 65.4 ΔV_(f) 8  8 · ΔV_(f)16 0 50 24 · 40 8 60 19 · ΔV_(f) 29 9 65.5 ΔV_(f) 9  9 · ΔV_(f) 18 0 5027 · 45 9 60 21 · ΔV_(f) 32 10 65.6 ΔV_(f) 10 10 · 20 0 50 30 · 50 10 6023 · ΔV_(f) 35 11 65.7 ΔV_(f) ΔV_(f) 21 21 · 42 0 50 63 · 105 21 60 45 ·ΔV_(f) 68 22 66.2 ΔV_(f) ΔV_(f) 30 30 · 60 0 50 90 · 150 30 60 63 ·ΔV_(f) 95 31 66.3 ΔV_(f) ΔV_(f) 63 63 · 126 0 50 — — — — — — — — ΔV_(f)

Therefore, in a case in which an output of nine LED devices arerequired, the reverse parallel LED circuit illustrated in FIG. 186Arequires a total of eighteen LED devices, and the bridge network LEDcircuit requires a total of fifteen LED devices to define three stages.Meanwhile, in the ladder network LED circuit according to the embodimentof the present invention, a total of fourteen LEDs are connected todefine three stages, thereby providing desired light amount (nine LEDdevices). This leads to a considerable decrease in the number ofemployed LED devices compared with the bridge LED circuit.

This improvement is further achieved in the circuit with a higheroutput. That is, in a case in which an output of sixty three LED devicesis required, the reverse parallel circuit and the bridge circuit requireone hundred twenty six and one hundred five LED devices, respectively,to enable AC driver circuit. However, the ladder network LED circuitrequires only ninety five LED devices, thereby reducing the number ofthe LED devices by 31 and 10, respectively, compared with theconventional circuit.

This is because in the bridge LED circuit, at least two LED devices arelocated in a current loop between the LEDs commonly drivenbi-directionally. Meanwhile, in the ladder network, at least one LEDdevice is required between the LED devices commonly used. That is, theladder network circuit requires a smaller number of LEDs between theLEDs commonly used bi-directionally than the bridge network circuit.This allows the ladder network to commonly use a larger number of LEDsbi-directionally than the bridge structure.

FIG. 187A illustrates an LED driver circuit according to anotherconventional example, and FIG. 187B illustrates an LED driver circuitaccording to another embodiment of the present invention.

The LED driver circuits of FIGS. 187A and 187B are similar to those ofFIGS. 186A and 186B but configured such that two LED devices arearranged in each middle branch. That is, the number of continuouslydriven LED devices is increased to an equal level in each stage. Theladder network LED driver circuit shown in FIG. 187B will be understoodwith reference to the embodiment shown in FIG. 184B.

TABLE 5 Reverse parallel network Bridge network Ladder network No. ofNo. of No. No. of No. of No. of bi-direction Efficiency No. ofbi-direction Efficiency of bi-direction Efficiency stages V_(f) LEDturns (%) V_(f) LED turns (%) V_(f) LED turns (%) 1 ΔV_(f) 2 0 50  4 ·ΔV_(f) 6 2 66.7  7 · ΔV_(f) 10 4 70 2  2 · ΔV_(f) 4 0 50  8 · ΔV_(f) 124 66.7 10 · ΔV_(f) 14 6 71.4 3  3 · ΔV_(f) 6 0 50 12 · 18 6 66.7 13 ·ΔV_(f) 18 8 72 ΔV_(f) 4  5 · ΔV_(f) 8 0 50 16 · 24 8 66.7 16 · ΔV_(f) 2210 72.7 ΔV_(f) 5  5 · ΔV_(f) 10 0 50 20 · 30 10 66.7 19 · ΔV_(f) 26 1273.1 ΔV_(f) 6  6 · ΔV_(f) 12 0 50 24 · 36 12 66.7 22 · ΔV_(f) 30 14 73.3ΔV_(f) 7  7 · ΔV_(f) 14 0 50 28 · 42 14 66.7 25 · ΔV_(f) 34 16 73.5ΔV_(f) 8  8 · ΔV_(f) 16 0 50 32 · 48 16 66.7 28 · ΔV_(f) 38 18 73.7ΔV_(f) 9  9 · ΔV_(f) 18 0 50 36 · 54 18 66.7 31 · ΔV_(f) 42 20 73.8ΔV_(f) 10 10 · 20 0 50 40 · 60 20 66.7 34 · ΔV_(f) 46 22 73.9 ΔV_(f)ΔV_(f) 13 13 · 26 0 50 52 · 78 26 66.7 43 · ΔV_(f) 58 28 74 ΔV_(f)ΔV_(f) 16 16 · 32 0 50 64 · 96 32 66.7 52 · ΔV_(f) 70 34 74.3 ΔV_(f)ΔV_(f) 52 52 · 104 0 50 — — — — — — — — ΔV_(f)

Therefore, in a case in which an output of sixteen LED devices isrequired, the reverse-parallel LED circuit illustrated in FIG. 186Arequires a total thirty two LED devices, and the bridge network LEDcircuit illustrated in FIG. 187A requires a total twenty four LEDdevices to define four stages. Meanwhile, in the ladder network LEDcircuit according to the embodiment of the present invention, a totaltwenty two LED devices are required to provide desired light amount(sixteen LED devices), leading to a considerable reduction in the numberof the employed LED devices compared with the bridge LED circuit.

This improvement is further achieved in the circuit with a higheroutput. That is, in a case in which an output of fifty two LED devicesis required, the reverse parallel circuit and the bridge circuit requireone hundred four and seventy eight LED devices, respectively, to enableAC driver circuit. However, the ladder network LED circuit requires onlyseventy LED devices, thereby reducing the number of the LED devices by34 and 8, respectively, compared with the conventional circuit.

As described above, the ladder network LED driver circuit requires asmaller number of LED devices for AC driving to achieve identical outputthan the conventional reverse parallel structure and the bridgestructure as well.

The following description will be made regarding an automatic LEDdimming apparatus which is capable of reducing power consumption byautomatically adjusting the brightness of an LED in a surface lightsource and a backlight employing a light emitting package according tovarious embodiments of the present invention, depending on a surroundingbrightness.

FIG. 188 is a configuration diagram of an automatic LED dimmingapparatus according to an embodiment of the present invention. Referringto FIG. 188, the automatic LED dimming apparatus includes a surroundingbrightness detection unit 5700 detecting a surrounding brightness, adimming control unit 5800 controlling a driving according to a magnitudeof a detection voltage Vd generated by the detection of the surroundingbrightness detection unit 5700, and a dimming driving unit 5810generating an LED driving current according to the driving control ofthe dimming control unit 5800. Furthermore, the automatic LED dimmingapparatus may include an LED unit 5820 including a plurality of LEDs anddriven according to a driving current of the dimming driving unit 5810.

The surrounding brightness detection unit 5700 may include a sensitivitysetting unit 5710 setting a detection sensitivity for detection of asurrounding brightness, and a photo sensor unit 5720 receiving anexternal light and detecting a surrounding brightness at the detectionsensitivity set by the sensitivity setting unit 5710. The photo sensorunit 5720 may include a photo transistor PT having a collector connectedto a power supply terminal through which an operating voltage Vcc issupplied, a base receiving an external light, and an emitter connectedto the sensitivity setting unit 5710. The sensitivity setting unit 5710may include a variable resistor connected to the emitter of the phototransistor PT and adjustable by a user, and a resistor seriallyconnected to the variable resistor.

Upon operation of the automatic LED dimming apparatus, the surroundingbrightness detection unit 5700 detects a surrounding brightness andoutputs a detection voltage Vd to the dimming control unit 5800. Forexample, when the surrounding brightness detection unit 5700 includesthe sensitivity setting unit 5710 and the photo sensor unit 5720, thesensitivity setting unit 5710 may set a detection sensitivity fordetection of the surrounding brightness with respect to the photo sensorunit 5720. The photo sensor unit 5720 may receive an external light anddetect the surrounding brightness at the detection sensitivity set bythe sensitivity setting unit 5710. In this case, the photo sensor unit5720 may be implemented with a photo resistor PT having a collectorconnected to a power supply terminal through which an operating voltageVcc is supplied, a base receiving the external light, and an emitterconnected to the sensitivity setting unit 5710. When the phototransistor PT receives the external light, it is turned on so that acurrent I flows from the operating voltage (Vcc) terminal to the phototransistor PT and the sensitivity setting unit 5710. That is, thecurrent I is detected as the detection voltage Vd by the sensitivitysetting unit 5710. When the sensitivity setting unit 5710 is connectedto the emitter of the photo transistor PT and implemented with theavailable resistor and the resistor, the current I is changed accordingto the resistance of the variable resistor, and the slope of thedetection voltage Vd is changed according to the current I.

The dimming control unit 5800 includes an analog/digital (ND) converter5801 converting the analog detection voltage Vd generated by thedetection of the surrounding brightness detection unit 5700 into adigital detection voltage, and a micom 5802 controlling a drivingaccording to the magnitude of the digital detection voltage Vd outputtedfrom the ND converter 5801. When the digital detection voltage Vd fromthe ND converter 5801 is lower than a preset first reference voltage,the micom 5802 may generate a driving current preset according to themagnitude of the difference voltage between the first reference voltageand the first reference voltage. When the digital detection voltage Vdis not lower than the first reference voltage, the micom 5802 may stopan illumination driving.

The operation of the dimming control unit 5800 will be described belowin more detail. The dimming control unit 5800 controls the driving ofthe dimming driving unit 5810 according to the magnitude of thedetection voltage Vd generated by the detection of the surroundingbrightness detection unit 5700. for example, when the dimming controlunit 5800 includes the ND converter 5801 and the micom 5802, the NDconverter 5801 converts the analog detection voltage Vd generated by thedetection of the surrounding brightness detection unit 5700 into adigital detection voltage, and outputs the digital detection voltage tothe micom 5802. The micom 5802 may control the driving according to themagnitude of the digital detection voltage Vd outputted from the NDconverter 5801.

The dimming driving unit 5810 generates an LED driving current accordingto the driving control of the dimming control unit 5800, and providesthe generated LED driving current to the LED unit 5820. Consequently,the dimming driving unit 5810 generates a small driving current whenthere is much external light amount, and generates a large drivingcurrent when there is little external light amount. Accordingly, the LEDunit 5820 may include a plurality of LEDs, which are driven according tothe driving current from the dimming driving unit 5810. As describedabove, the brightness of the LEDs may be automatically adjustedaccording to the external light amount, and the power consumption may bereduced to the minimum level.

FIG. 189 is an operation flowchart of the automatic LED dimmingapparatus according an embodiment of the present invention. Referring toFIG. 1890, S1 is a step of receiving a detection voltage Vd. S2 is astep of comparing a digital detection voltage Vd with a preset firstreference voltage. S3 is a step of controlling illumination brightnessby generating a driving current which is preset according to themagnitude of a difference voltage between the first reference voltageand the digital detection voltage Vd when a digital detection voltage Vdis lower than a preset first reference voltage. S4 is a step of stoppingthe illumination driving when the digital detection voltage Vd is notlower than the first reference voltage. S5 is a step of determiningwhether to stop the operation. When it is determined not to stop theoperation at step S5, the procedures of steps S1 to S3 are repeated. Itis determined to stop the operation at step S5, the entire proceduresare ended.

Referring to FIGS. 188 and 189, the micom 5802 receives the digitaldetection voltage Vd from the ND converter 5801 (S1), and compares thedigital detection voltage Vd with the preset first reference voltage(S2). The micom 5802 controls the illumination brightness by generatingthe driving current which is preset according to the magnitude of thedifference voltage between the first reference voltage and the digitaldetection voltage Vd when the digital detection voltage Vd from the NDconverter 5801 is lower than the first reference voltage (S3). The micom5802 may stop the illumination driving when the digital detectionvoltage Vd is not lower than the first reference voltage (S4).Meanwhile, the micom 5802 determines whether to stop the operation (S5).When the micom 5802 determines not to stop the operation, it repeats theprocedures of steps S1 to S3. When the micom 5802 determines to stop theoperation, it ends the entire procedures.

FIG. 190 is an external luminance-detection voltage relationship graphaccording to an embodiment of the present invention. Specifically, FIG.190 is an external luminance-detection voltage relationship graphexplaining the operation of the surrounding brightness detection unit5700 according to the embodiment of the present invention. The externalluminance-detection voltage graph exhibits that the detection voltageincreases with the increase of the external luminance. Referring to theexternal luminance-detection voltage relationship graph of FIG. 190, thedetection voltage of the surrounding brightness detection unit 5700becomes higher as the external luminance increases.

FIG. 191 is various external luminance-detection voltage relationshipgraphs according to the sensitivity setting according to the embodimentof the present invention. FIG. 191 shows an example in which a slope ofthe external luminance-detection voltage relationship graph is changedaccording to the sensitivity setting of the sensitivity setting unit5710 included in the surrounding brightness detection unit 5700. Amongthree graphs illustrated in FIG. 191, the graph G1 is an externalluminance-detection voltage relationship graph having a middle slope,the graph G2 is an external luminance-detection voltage relationshipgraph having the greatest slope, and the graph G3 is an externalluminance-detection voltage relationship graph having the smallestslope.

Referring to FIG. 191, when the sensitivity is set differently byadjusting the variable resistor included in the sensitivity setting unit5710 of the surrounding brightness detection unit 5700, the slope of theexternal luminance-detection voltage relationship graph is changed, likethe graphs G1, G2 and G3 of FIG. 191. For example, in a normal case, thesensitivity is set to a level corresponding to the graph G1. In a casein which there is a large amount of external light and there is a greatchange therein, the sensitivity is set to a level corresponding to thegraph 2. In a case in which there is a small amount of external lightand there is a slight change therein, the sensitivity is set to a levelcorresponding to the graph G3.

A vehicle headlight including the light emitting device including alight emitting device and a light emitting device package as a lightsource will be described below with reference to FIGS. 192 through 197.

FIG. 192 is an exploded perspective view of a vehicle headlightaccording to an embodiment of the present invention, and FIG. 193 is across-sectional view illustrating an assembly of the vehicle headlightof FIG. 192.

Referring to FIG. 192, the vehicle headlight 6000 includes lightemitting device packages 6010, 6010-1, 6010-2 and 6010-3, a reflectionunit 6020, a lens unit 6030, and a heat dissipation unit 6040. The lightemitting device packages 6010, 6010-1, 6010-2 and 6010-3 are mounted onthe heat dissipation unit 6040 and electrically connected to an externalpower supply (not shown). The light emitting device packages 6010,6010-a, 6010-2 and 6010-3 function as a light source to emitting lightwhen a voltage is supplied.

Various structures of the light emitting device packages 6010, 6010-1,6010-2 and 6010-3 will be described below in more detail with referenceto FIGS. 194 through 197. First, a light emitting device package inwhich a resin layer includes a phosphor will be described with referenceto FIGS. 194 and 196.

FIG. 194A is a plan view of a light emitting device package according toan embodiment of the present invention, FIG. 194B is a cross-sectionalview of the light emitting device package of FIG. 194A, and FIG. 194C isa plan view illustrating modified examples of the light emitting devicepackage of FIG. 194 in which a light emitting device chip is mounted.

FIG. 195A is a plan view of a light emitting device package according toanother embodiment of the present invention, FIG. 195B is across-sectional view of the light emitting device package of FIG. 195A,and FIGS. 195C and 195D are plan views illustrating modified examples ofthe light emitting device package of FIG. 195A in which a light emittingdevice chip is mounted.

Referring to FIGS. 194 and 195, the light emitting device packages 6010and 6010-1 include at least one light emitting device chip 6012, asubstrate 6011, and a resin layer 6014. The light emitting device chip6012 is mounted on the substrate 6011, and the substrate 6011 includesat least one connection terminal 6013 electrically connected to thelight emitting device chip 6012. The resin layer 6014 includes aphosphor and seals the light emitting device chip 6012 and theconnection terminal 6013. The light emitting device chip 6012 is mountedon the top surface of the substrate 6011, and is a type of asemiconductor device which emits light of a predetermined wavelength byan external voltage. Referring to FIGS. 194A, 194B, 195A and 195B, theplurality of light emitting device chip 6012 may be provided at thecenter portion of the substrate 6011. In this case, when the lightemitting device chip 6012 is a blue light emitting device, the lightemitting device packages 6010 and 6010-1 may further include a phosphorfor providing a white light, and the phosphor may include a yellowphosphor. For example, the white light may be obtained by injecting agel-type epoxy resin containing a YAG-based yellow phosphor, or agel-type silicon resin containing a YAG-based yellow phosphor into thereceiving groove of the package and performing an ultraviolet curing ora thermal curing thereon, or coating or stacking a phosphor layer on thetop surface of the chip.

The present invention is not limited to the light emitting devicepackage including the blue light emitting device and the yellow lightemitting device. For example, the light emitting device package mayinclude a near ultraviolet chip, and a resin encapsulation part in whicha red phosphor, a green phosphor, and a blue phosphor provided on thenear ultraviolet chip are mixed, or a resin encapsulation part in whicha red phosphor, a green phosphor, and a blue phosphor are sequentiallystacked. Also, the light emitting device chip emitting ultraviolet lightor blue light may be a white light emitting device package whichincludes an inorganic compound or at least one of a silicate-basedphosphor, a garnet-based phosphor, a sulfide-based phosphor, anitride-based phosphor, and a QD phosphor, wherein the inorganiccompound is expressed as the composition of (Sr, M)₂SiO_(4-x)N_(y):Eusynthesized in the above-described embodiments 1 through 11.

Alternatively, the light emitting device chips 6012 may be arrayed withthe combination of a blue light emitting device, a red light emittingdevice, and a green light emitting device and configured to generate awhite light. However, the present invention is not limited to the aboveembodiment. As illustrated in FIGS. 194C and 195C, a single white lightemitting device 6012′ may be provided at the center portion of thesubstrate 6010. In this case, the light emitting device chip 6012′ maybe a blue light emitting device or an ultraviolet (UV) light emittingdevice. A white light is emitted through the phosphor of the resin layer6014, which will be described layer.

Also, as illustrated in FIGS. 194D and 195D, short light emitting devicechips 6012 may be symmetrically provided on both sides of a long lightemitting device chip 6012″ provided at the center portion of thesubstrate 6011. In this case, the light emitting device chip 6012″provided at the center portion of the substrate 6011 may be 1.5 to 2times longer than the light emitting device 6012 provided on both sidesof the light emitting device chip 6012″. The light emitting device chip6012″ may be, but is not limited to, a green light emitting device. Thelighting device chip 6012 is electrically connected through a metal wire6019 to the connection terminal 6013 patterned on the top surface of thesubstrate 6011 in a wire bonding method.

Referring to FIGS. 194A and 194B illustrating the light emitting devicepackage 6000 according to the embodiment of the present invention, thesubstrate 6010 includes a cavity 6018. The light emitting device chip6012 is mounted on the top surface of the cavity 6018, and theconnection terminal 6013 is mounted inside the cavity 6018. The cavity6918 forms a reflection surface 6016 along an inner periphery surfaceinclined downward to the light emitting device chip 6012 and theconnection terminal 6013. The cavity 6018 may be provided by recessingthe top surface of the substrate 6011 at a predetermined size through alaser or an etching process, or may be provided by molding the resinlayer 6017 along the perimeter of the top surface of the substrate 6011at a predetermined height so that the reflection surface 6016 protrudes.In order for further efficient implementation of the reflection surface6016, a reflective layer having a high reflectivity may be furtherprovided on the reflection surface 6016.

The cavity 6018 is filled with a resin layer 6014 including a phosphor,and integrally covers and seals the light emitting device chip 6012, themetal wire 6019, the connection terminal 6013, and the top surface ofthe substrate 6011, thereby protecting the light emitting device chip6012 and so on disposed within the cavity 6018. In this case, the lightemitting device package 6000 is configured so that the top and sidesurfaces of the light emitting device chip 6012, including the intervalbetween the light emitting device chips 6012, is sealed by the resinlayer 6014.

Therefore, it is possible to solve the problem of the conventional lightemitting device package that irradiated light appears to be notcontinuous but discontinuously separated because the phosphor is coatedon only the top surface of the light emitting device chip.

Meanwhile, referring to FIGS. 195A and 195B illustrating a lightemitting device package 6010-1 according to another embodiment of thepresent invention, the resin layer 6014 is molded on the flat topsurface of the substrate 6000-1 at a predetermined size and height tointegrally cover and seal the light emitting device chip 6012 and theconnection terminal 6013. In this case, the light emitting device chip6000-1 is configured so that the top and side surfaces of the lightemitting device chip 6012, including the interval between the lightemitting device chips 6012, is sealed by the resin layer 6014.

Next, a light emitting device package including a phosphor layer whichis formed on the top surface of a resin layer and includes a phosphorlayer containing a phosphor to convert wavelength of light emitted froma light emitting device chip, will be described with reference to FIGS.196 and 197. FIG. 196A is a plan view illustrating another embodiment ofthe light emitting device package of FIG. 194A, FIG. 196B is across-sectional view of the light emitting device package of FIG. 196A,and FIG. 196C is a cross-sectional view illustrating a modifiedembodiment of the light emitting device package of FIG. 196B.

The structure of the light emitting device package 6010-2 illustrated inFIG. 196 is substantially identical to that of the embodimentillustrated in FIG. 194, except that the phosphor layer including thephosphor is provided on the top surface of the resin layer. Thus, adetailed description about the same elements as the embodiment of FIG.194 will be omitted, and only different elements will be describedbelow.

Referring to FIG. 196, the resin layer 6014 filling the cavity 6018 andintegrally covering and sealing the light emitting device chip 6012, themetal wire 6019, the connection terminal 6013, and the top surface ofthe substrate 6011 does not include a phosphor. However, like theembodiment of FIG. 194, the resin layer 6014 integrally seals the topand side surfaces of the light emitting device chip 6012, including theinterval between the light emitting device chips 6012, and theconnection terminal 6013. The resin layer 6014 includes a phosphor layer6015 including a phosphor on the top surface thereof to convertwavelength of light emitted from the light emitting device chip 6012.Although the phosphor layer 6015 provided on the top surface of theresin layer 6014 is illustrated, it may be coated on the outer side ofthe resin layer 6015, or may be attached to the outer surface of theresin layer 6014 in a layer form. In this case, the phosphor layer 6015may be provided by at least one stacked layer.

Referring to FIG. 196B, the phosphor is included within the phosphorlayer 6015 in order to convert the wavelength of light. The phosphor maybe provided by mixing at least one phosphor of a blue phosphor, a greenphosphor, a red phosphor, and a yellow phosphor. In addition, althoughthe multi-layer structure (three layers are stacked in the drawing) isillustrated in FIG. 196C, the present invention is not limited thereto.In this case, the stacked phosphor layer 6015 may include the samephosphor or different phosphors in layers. In the stacked phosphor layer6015, the phosphor layer having a short wavelength is disposed on theupper portion, and the phosphor layer having a long wavelength isdisposed on the lower portion. In this manner, the phosphor layers aresequentially stacked according to the wavelength.

For example, when the light emitting device chip 6012 is a UV lightemitting device chip, a first phosphor layer 6015′-1 formed on the lightemitting device chip 6012 may be provided with a mixture of a redphosphor and a resin. The red phosphor emitting a red light (R) may beformed of a phosphor material which is excited by ultraviolet light andhas a peak emission wavelength of approximately 600-700 nm. A secondphosphor layer 6015′-2 is stacked on the first phosphor layer 6015′-2and may be provided with a mixture of a green phosphor and a resin. Thegreen phosphor emitting a green light (G) may be formed of a phosphormaterial which is excited by ultraviolet light and has a peak emissionwavelength of approximately 500-550 nm. A third phosphor layer 6015′-3is stacked on the second phosphor layer 6015′-3 and may be provided witha mixture of a blue phosphor and a resin. The blue phosphor emitting ablue light (B) may be formed of a phosphor material which is excited byultraviolet light and has a peak emission wavelength of approximately420-480 nm.

The ultraviolet light emitted from the UV light emitting device chipthrough the above-described structure excite different kinds of thephosphors included in the first phosphor layer 6015′-1, the secondphosphor layer 6015′2, and the third phosphor layer 6015′-3.Accordingly, the red light (R), the green light (G), and the blue light(B) are emitted from the respective phosphor layers, and the three colorlights are mixed to generate a white light (W). In particular, when thephosphor layer for converting ultraviolet light is formed of amulti-layer structure, e.g., a three-layer structure, the first phosphorlayer 6015′-1 emitting the red light (R) having the longest wavelengthis stacked on the UV light LED chip 6012, and the second phosphor layer6015′-2 and the third phosphor layer 6015′3 emitting the green light (G)and the blue light (B) having a shorter wavelength than the red light(R) are sequentially stacked on the first phosphor layer 6015′-1.

Since the first phosphor layer 6015′-1 including the phosphor emittingthe red light (R) having the lowest light conversion efficiency isdisposed closest to the UV LED chip 6012, the light conversionefficiency at the first phosphor layer is relatively increased, therebyimproving the entire light conversion efficiency of the LED chip 6012.

When the light emitting device chip 6012 is a light emitting device chipemitting the red light (B) having the wavelength range of 420-480 nm asan excitation light, the first phosphor layer 6015′-1 formed on thelight emitting device chip 6012 is provided by a mixture of a redphosphor and a resin, and the second phosphor layer 6015′-2 and thethird phosphor layer 6015′-3 stacked on the first phosphor layer 6015′-1is provided by a mixture of a green or yellow phosphor and a resin.

The blue light (B) emitted from the light emitting device chip 6012through the above-described structure excites the phosphor included inthe first phosphor layer 6015′-1 to emit the red light (R), and excitesthe phosphors included in the second and third phosphor layers 6015′-2and 6015′-3 to emit the green light (G) or the yellow light (Y). The redlight (R) and the green light (G) (or the yellow light (Y)) emitted fromthe multi-layer phosphor layer and the blue light (B) emitted from thelight emitting device chip are mixed to generate a white light (W).

Meanwhile, FIG. 197 a is a plan view illustrating another embodiment ofthe light emitting device package of FIG. 195A, FIG. 197B is across-sectional view of the light emitting device package illustrated inFIG. 197A, and FIG. 197C is a cross-sectional view illustrating amodified embodiment of FIG. 197B.

The structure of the light emitting device package 6010-3 illustrated inFIG. 197 is substantially identical to that of the embodimentillustrated in FIG. 195, except that the phosphor layer including thephosphor is provided on the side surface of the rein layer. Thus, adetailed description about the same elements as the embodiment of FIG.195 will be omitted, and only different elements will be describedbelow.

Referring to FIG. 197, the resin layer 6014 provided on the flat topsurface of the substrate 6010 and integrally covering and sealing thelight emitting device chip 6012, the metal wire 6019, the connectionterminal 6013, and the top surface of the substrate 6011 does notinclude a phosphor. Also, the embodiment of FIG. 197 is substantiallyidentical to the embodiment of FIG. 196 in that the resin layer 6014does not include a phosphor and the phosphor is included within thephosphor layer 6015 provided on the top surface of the resin layer 6014.

Referring to FIG. 197B, the phosphor included within the phosphor layer6015 may be provided by mixing at least one phosphor of a blue phosphor,a green phosphor, a red phosphor, and a yellow phosphor. In addition,although the multi-layer structure (three layers are stacked in thedrawing) is illustrated in FIG. 197C, the present invention is notlimited thereto. In this case, the stacked phosphor layer 6015 mayinclude the same phosphor or different phosphors in layers.

In the stacked phosphor layer 6015, the phosphor layer having a shortwavelength is disposed on the upper portion, and the phosphor layerhaving a long wavelength is disposed on the lower portion. Since thedetailed structure of the phosphor 6015 is substantially identical tothe phosphor layers 6015 of FIGS. 196B and 196C, a detailed descriptionthereof will be omitted.

The heat dissipation unit 6040 includes a heat sink 6040 and a coolingfan 6042. Since the light emitting device packages 6010, 6010-1, 6010-2and 6010-3 are provided on the heat dissipation unit 6040, heatgenerated from the light emitting device packages 6010, 6010-1, 6010-2and 6010-3 are emitted to the outside.

Specifically, the heat sink 6041 is mounted on the top surfaces of thelight emitting device packages 6010, 6010-1, 6010-2 and 6010-3, andhigh-temperature heat generated from the light emitting device packages6010, 6010-1, 6010-2 and 6010-3 is emitted to the outside. In this case,a plurality of grooves may be formed on the bottom surface in order toobtain a wide surface area. The cooling fan 6042 is mounted under theheat sink 6041 to increase the heat dissipation efficiency of the heatsink 6041.

The reflection unit 6020 is provided on the light emitting devicepackages 6010, 6010-1, 6010-2 and 6010-3 and the heat dissipation unit6040 to guide and reflect light emitted from the light emitting devicepackages 6010, 6010-1, 6010-2 and 6010-3. As illustrated in FIGS. 192and 193, the reflection unit 6020 is formed to have a dome-shapedcross-section and guides light emitted from the light emitting devicechip 6012 in the front of the vehicle. Also, the reflection unit 6020has an opened front side and emits the reflected light to the outside.

The vehicle headlight 6000 according to this embodiment of the presentinvention further includes a housing 6050 fixing and supporting the heatdissipation unit 6040 and the reflection unit 6020. Specifically, acenter hole 6050 is formed on a first side of the housing 6050 so thatthe heat dissipation unit 6040 is connected and mounted on the firstside of the housing 6050. A front hole 6052 is formed on the second sideintegrally connected to the first side and bent at the right angle, sothat the reflection unit 6020 is disposed on the top surface of thelight emitting device packages 6010, 6010-1, 6010-2 and 6010-3.

Therefore, the reflection unit 6020 is fixed to the housing 6050 so thatthe opened front side of the reflection unit 6020 corresponds to thefront hole 6052. Thus, the light reflected by the reflection unit 6020is emitted to the outside through the front hole 6052.

The lens unit 6030 emits the light reflected by the reflection unit 6020to the outside. The lens unit 6030 includes a hollow guide 6032 and alens 6061. Specifically, the guide 6032 is mounted along the front hole6052 of the housing 6050 and guides the light reflected by thereflection unit 6020 and passing through the front hole 6052 in a frontdirection. The guide 6032 has a hollow cylindrical structure in whichthe lens 6031 is received. The guide 6032 is an injected plastic productformed by injection molding.

The lens 6031 may be mounted on the front side of the guide 6032 torefract and disperse the light in a front direction of the vehicle, andmay be formed of a transparent material.

The illumination apparatus such as the backlight unit and the vehicleheadlight according to the various embodiments of the present inventionmay employ the above-described various light emitting device packages.The light emitting device package may include an inorganic compound orat least one of a silicate-based phosphor, a garnet-based phosphor, asulfide-based phosphor, a nitride-based phosphor, and a QD phosphor,wherein the inorganic compound is expressed as the composition of (Sr,M)₂SiO_(4-x)N_(y):Eu synthesized in the above-described embodiments 1through 11, where M is at least one of monad or dyad elements, 0<x<4,and y=2x/3. The light emitting device package includes a wavelengthconversion unit or a resin encapsulation unit for absorbing lightemitted from the LED chips and converting the wavelength of the emittedlight.

As set forth above, exemplary embodiments of the invention provide thevertical type semiconductor light emitting device which is capable ofimproving external light extraction efficiency, specifically, laterallight extraction efficiency.

While the present invention has been shown and described in connectionwith the exemplary embodiments, it will be apparent to those skilled inthe art that modifications and variations can be made without departingfrom the spirit and scope of the invention as defined by the appendedclaims.

1. A semiconductor light emitting device, comprising: a conductivesubstrate; a light emitting structure including a first-conductivitytype semiconductor layer, an active layer, and a second-conductivitytype semiconductor layer which are sequentially formed on the conductivesubstrate; a second-conductivity type electrode including: a conductivevia passing through the first-conductivity type semiconductor layer andthe active layer and connected to the inside of the second-conductivitytype semiconductor layer; and an electrical connection part extendingfrom the conductive via and exposed to the outside of the light emittingstructure; an insulator electrically separating the second-conductivitytype electrode from the conductive substrate, the first-conductivitytype semiconductor layer, and the active layer; a passivation layerformed to cover at least a side surface of the active layer in the lightemitting structure; and an uneven structure formed on a path of lightemitted from the active layer.
 2. A semiconductor light emitting device,comprising: a conductive substrate; a light emitting structure includinga first-conductivity type semiconductor layer, an active layer, and asecond-conductivity type semiconductor layer which are sequentiallyformed on the conductive substrate; a first contact layer electricallyconnected to the first-conductivity type semiconductor layer between theconductive substrate and the first-conductivity type semiconductor layerand exposed to the outside of the light emitting device; a conductivevia extending from the conductive substrate, passing through the firstcontact layer, the first-conductivity type semiconductor layer, and theactive layer, and electrically connected to the inside of thesecond-conductivity type semiconductor layer; an insulator electricallyseparating the conductive substrate from the first contact layer, thefirst-conductivity type semiconductor layer, and the active layer; apassivation layer formed to cover at least a side surface of the activelayer in the light emitting structure; and an uneven structure formed ona path of light emitted from the active layer.
 3. The semiconductorlight emitting device of claim 1, further comprising a second contactlayer formed between the first-conductivity type semiconductor layer andthe conductive substrate and electrically separated from thesecond-conductivity type electrode by the insulator.
 4. Thesemiconductor light emitting device of claim 1, wherein the lightemitting structure is formed only on a portion of the top surface of theconductive substrate, and an etch stop layer formed on at least a regionin which the light emitting structure is not formed over the top surfaceof the conductive substrate, the etch stop layer having an etchingcharacteristic different from a semiconductor material constituting thelight emitting structure.
 5. The semiconductor light emitting device ofclaim 1, wherein the uneven structure is formed on the top surface ofthe second-conductivity type semiconductor layer.
 6. The semiconductorlight emitting device of claim 1, wherein the first-conductivity typesemiconductor layer and the second-conductivity type semiconductor layerare a p-type semiconductor layer and an n-type semiconductor layer,respectively.